ECAdd no longer takes is_infinite operands. Update the transpiler,
inline ECADD handler, and MSM procedure to use the new (x, y) point
layout with (0, 0) as the point at infinity.

Regenerate acir.hpp from noir's autogen and propagate the resulting
shape changes through the dsl:
- ECAdd / MSM no longer carry is_infinite; (0, 0) is now the point at
  infinity throughout EcAdd, MultiScalarMul, and to_grumpkin_point.
- MemOp switches from three Expressions (operation, index, value) to
  (read: bool, index: Witness, value: Witness).
- Circuit drops current_witness_index.

Tests that exercised the externally-supplied infinity flag have been
dropped since the flag no longer exists; (0,0)-roundtrip cases are kept.

Acir::MemOp no longer accepts Expression-shaped index/value after the
serialization change; mem_op_to_acir_mem_op now asserts both are
witnesses. The ROM/RAM/CallData test configs that exercised constant
ops (perform_constant_ops = true) round-trip through that helper and
trip the assertion, so drop those configs together with the unused
add_constant_ops helper and template flag.

EmbeddedCurveAdd dropped is_infinite in 4992cb1, so each MSM point is
now two field elements and the output is (x, y). The two size assertions
were missed in that change; update them to match.

EmbeddedCurveAdd/MSM dropped is_infinite from points (4992cb1).
The constraint now uses 6 fewer gates for MSM and 8 fewer for EcAdd,
so update the opcode-gate-count expectations to match.

…#22921)

This branch solely contains the changes needed to remove the
`is_infinite` flag from our `StandardAffinePoint` C++ wrapper. Now, we
check whether `x` and `y` are zero to assign an `inf` underlying point.

Will close [Foundation AVM Issue
17](https://linear.app/aztec-foundation/issue/AVM-17/remove-is-inf-flag-from-avms-standardaffinepoint)

---

Stack:

- #22745
- #22564
- `mw/avm-rem-inf-point-wrapper` <-- here
- #22795
- #22945
- #23031

…y) (#22795)

This branch includes the changes to remove the `is_infinite` flag from
our point representation and conceptually treating a point as infinite
iff its coordinates are `(0, 0)`.

It only contains logic changes within the AVM for the above and does not
touch the opcode - this is in a lower PR - so the **CI will probably
fail**.

Will close [Foundation AVM Issue
18](https://linear.app/aztec-foundation/issue/AVM-18/remove-is-inf-flag-from-resulting-ec-points-in-avm-circuits)

---

Stack:
- #22745
- #22564
- #22921
- `mw/avm-explore-remove-is-inf` <-- here
- #22945
- #23031

…#22945)

This branch includes the changes to remove the `is_infinite` flags from
the ECADD opcode fn signature. The actual EC logic changes come above
this PR in the stack, and any changes outside the AVM will be below.

For ease of review, I've separated into commits:

- **feat: remove inf flags from ecadd opcode - ec flow only** Isolated
to the EC flow only (does not change registers so non avm tests will
fail)
- f**eat: rem infs from fuzzer (only gadget fuzzer tested)** Isolated
fixes to get the fuzzer(s) compiling

Will partially close [Foundation AVM Issue
19](https://linear.app/aztec-foundation/issue/AVM-19/) (the following PR

Note that the opcode mismatches that in ts so **CI will fail** until

---

Stack:
- #22745
- #22564
- #22921
- #22795
- `mw/avm-rem-inf-opcode-ecadd` <-- here
- #23031

… AVM only) (#23031)

This branch includes the changes to remove the `is_infinite` flags from
the ECADD opcode fn signature which reside outside `vm2`. This includes
the transpiler, ts simulator, and anything required in ACIR.

Note that ACIR and noir's black box still use [the
flags](https://github.com/AztecProtocol/aztec-packages/blob/b30fe8f401d7af45148071924b22b3f377750eaf/barretenberg/cpp/src/barretenberg/dsl/acir_format/ec_operations.hpp#L34)
and represent points by a[ triple of
elements.](https://github.com/noir-lang/noir/blob/bc4a37e2994ebc7d44ae98be81e18606b2231c61/acvm-repo/bn254_blackbox_solver/src/embedded_curve_ops.rs#L98)
Since this touches both private and public execution, I think it's out
of scope of this task to update these.

Will partially close [Foundation AVM Issue
19](https://linear.app/aztec-foundation/issue/AVM-19/) (the previous PR
with AVM changes will close the initial portion)

---

Stack:
- #22745
- #22564
- #22921
- #22795
- #22945
- `mw/avm-rem-inf-opcode-ecadd-ext` <-- here

### Update

Will also close [Foundation AVM Issue
13](https://linear.app/aztec-foundation/issue/AVM-13/enforce-canonical-point-at-infinity-representation)

Note that this is currently being used as a base for removing the flag
from AVM's point representation ([Foundation AVM Issue
14](https://linear.app/aztec-foundation/issue/AVM-14/remove-is-inf-flag-from-avm-ec-point-representation)):

- ~#22745 (in merge
train)
- #23342 (ACIR
changes from #23155 for removing `inf`)
- #22564 <-- here
- #22921 ✅ 
- #22795 ✅ 
- #22945 ✅ 
- #23031 ✅ 


**Everything in this branch has been reviewed**, see above PRs for
individual work ⬆️


### [OLD] Overview

Will close
[AVM-248](https://linear.app/aztec-labs/issue/AVM-248/enforce-canonical-point-at-infinity-representation)

As a kind of stopgap before removing the `is_infinite` flag completely
from the AVM
([AVM-266](https://linear.app/aztec-labs/issue/AVM-266/remove-is-inf-flag-from-ec-point-representation)),
we now follow Noir behaviour more closely by deriving `is_inf` from
coordinates inside the circuits ( `(x, y) == (0, 0) ? is_inf == true`).
This replaces previous logic remapping points to (0, 0) from `is_inf`.

This method relies on the on curve check (for `(0, 0) ==> is_inf `) and
some new relations enforcing coordinates (for `is_inf ==> (0, 0)`)
rather than (more expensive) error handling. However this does mean that
the former will fail with an on curve error whereas the latter will
simply fail a relation.