feat[lang]: infer expected types

[charles-cooper]

What I did

rework validate_expected_type so that it returns (and tags) the expected type instead of just validating the type. this makes it so certain calls to validate_expected_type() can get a concrete type, where previously the type was not known beforehand.

this is a language change, generic bytes types (like from an interface) should work more as expected now.

How I did it

How to verify it

Commit message

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Cute Animal Picture

[fubuloubu]

too hard to evalulate changes until it's rebased on the module work