Fix: IPC AsyncMessageReader does not handle partial reads

[connortsui20]

Fixes: #5633

I doubt that the extra enums I added for readability will hurt performance in any meaningful way.

[connortsui20]

actually I just realized this does not handle EOF in the middle of a partial read as an error

[codecov]

Codecov Report

❌ Patch coverage is 94.68085% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.03%. Comparing base (baafc71) to head (475e3aa).

Files with missing lines	Patch %	Lines
vortex-ipc/src/messages/reader_async.rs	88.09%	5 Missing ⚠️

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[connortsui20]

@gatesn can you take a look again I made some changes

made changes