Various fixes reported from analyzer

[gasbytes]

f-904 - 3d50bbc check stat instead of only checking ret when verifying signatures (ed25519)
f-905 - 1a3db7b remove panic when signatures are invalid (verify/ecdsa.rs)
f-907 - ef80b36 copy_from_slice could panic when source and destination lengths differ, slice
indexing to prevent that. also the second copy_from_slice could overwrite the first one.
f-908 - 1cd5139 add missing RSA_PSS_SHA512 and RSA_PKCS1_SHA512 to the all array, which are already
supported.
f-917 - 5b2f5cb (aes256gcm) copy_from_slice could panic when source and destination lengths differ,
slice indexing to prevent that. also the second copy_from_slice could overwrite the first one.
f-909 - 5c0eb94 minor error in including ed448 as signature scheme in eddsa.rs
f-911 - 81d18aa match on any Err variant not just WCError when checking signatures in rsa-pkcs1 and
rsa-pss
f-918 - 3654c59 proper error mapping and return in sign/eddsa.rs instead of panic
f-914 - e7d5059 minor typo of the digest size in hmac_final (changed from sha3_384 to sha384)
f-906/915/916 - 9476a30 remove hmacobject dangling pointer, heap allocate hmac struct via box, so it outlives
hmac_init so that it remains valid for the lifetime of the hmac operation
f-910 - a91c8f1 check returned value of wc_HKDF_Expand with proper error propagation
f-912 - 9dc39df added drop implementations for the missing foreign types to prevent potential
resource leaking; custom deallocation method for rsa to reclaim the Box allocation; implemented Send and Sync to send the new rsa object safely between
threads
f-919 - d0f6ed0 use the appropriate copy function in the clone implementations of sha256 and sha384,
instead of doing bit by bit copies.
f-920 - b154c1f add lengths checks when deriving the secret in the p-* apis, to validate the peer
public key length before slicing (skipping 0x04 first byte) and return Result instead of panicking.
f-913 - 3d83b34 removing redundant check_if_zero, this was re-checking the wc_hmacfinal returned
value
f-921 - 254ec63 add zeroize crate to wipe key material from memory on drop (this applies for all the
crypto modules)