Add force_implicit_token_calling_convention flag to dslx to ir converter

[lsrcz]

This pull request adds a flag to the DSLX-to-IR converter that forces all functions to use the implicit-token calling convention.
We need this to enable IR transformations that insert assertions into existing programs, which requires converting the function to the implicit-token convention.
Previously, this was impossible because the activation bit could not be inferred from the converted IR alone.
To support this behavior, we introduce a new flag that instructs the converter to generate implicit tokens for all functions.

This includes a breaking change to the C API to include the flag.

[cdleary]

Did this change? hard to see

[lsrcz]

It is an auto formatter artifact and I reverted it.

[lsrcz]

The CI failure does not seem to be related.

xls/dslx/cpp_transpiler/cpp_transpiler_test.cc: Found non-absolute includes:
  path/to/some_types.h
  path/to/other_types.h
  /tmp/fake_path.h
  path/to/some_types.h
  path/to/other_types.h

[proppy]

@lsrcz can you confirm which version of xlsynth is compatible with this change?

[lsrcz]

@proppy This one was on top of commit 3646c63. Should I update to the latest main branch?

[proppy]

@proppy This one was on top of commit 3646c63. Should I update to the latest main branch?

Sorry I meant which version of the xlsynth's rust crate is compatible w/ this change.

[lsrcz]

@proppy I think it is compatible with xlsynth's rust crate since v0.6.0.

[proppy]

@proppy I think it is compatible with xlsynth's rust crate since v0.6.0.

understood, will make sure we import v0.6.0 before landing this /cc @hongted