Add IR conversion feedback to the DSLX interpreter

[magancarz]

This PR adds an IR conversion test to the DSLX interpreter enabled by lower_to_ir flag which is set by default. It performs the IR conversion check on every non-parametric proc or function and returns error if any fails. Tests can also be included in the check by adding convert_tests flag.

[rw1nkler]

FYI @richmckeever

[proppy]

should we also add this to typecheck_main?

[proppy]

This also need to be rebased.

[magancarz]

I've rebased changes on the latest main.

should we also add this to typecheck_main?

Sounds reasonable. @richmckeever what do you think?

[mikex-oss]

There seems to be no way to configure IR convert options through xls_dslx_test.

Rather than overloading xls_dslx_test in this way, what do we think about a separate xls_dslx_ir_convert_test or similar that just calls xls_dslx_ir + build_test? This is similar to how we have a separate xls_dslx_fmt_test, rather than doing it as check_formatting = True inside xls_dslx_test.

[magancarz]

@mikex-oss The intent behind IR conversion check when running DSLX tests was to prevent situations where the user would spend time on developing DSLX code that wouldn't be possible to convert to IR, which is an issue that would surface only when the user would run a xls_dslx_ir target. Moving this task to another target would make these changes unnecessary. @richmckeever What do you think?