[OSSIE][NVIDIA_GSF] Add bidirectional GSF semantic model converter

[johntomcat7408-cmyk]

Summary

• Add bidirectional conversion between Apache Ossie and NVIDIA GSF semantic-model YAML.
• Preserve SQL dialect semantics, field labels, native metadata, and relationship integrity.
• Support quoted dataset references and dialect-correct identifier quoting.
• Add regression coverage and a dedicated GSF converter CI workflow.

Context

This PR supersedes #247. The original implementation and discussion came from @liofnv; this replacement consolidates the change into one commit and incorporates the review fixes identified on #247.

Validation

• Added focused regression tests for quoted references, BigQuery quoting, field-label round trips, and relationship column validation.
• Added CI coverage for Python 3.11 through 3.14.
• Local tests were not run in this session.

[liofnv]

This PR contains the converter from #247, which I authored and opened on July 22. The code is substantially identical — ~95% of the non-empty lines in converters/gsf/src/ossie_gsf/converter.py here match #247 verbatim — but the commit is authored under a different name, so the history doesn't reflect the original authorship.

There's also a correctness problem. This copy is based on #247 as of commit 21aa2d3. That revision targeted a provisional GSF document shape predating GSF's actual interchange format. #247 has since been updated (791b440) to emit GSF's real GsfModelDocument contract, verified by importing the converter's output into a running GSF instance. As written, this PR would ship a GSF converter whose output GSF cannot import.

The CI workflow and regression tests added here are useful, and I'm happy to incorporate that idea into #247 with attribution.

I'd ask that this be closed in favor of #247.

[johntomcat7408-cmyk]

This PR contains the converter from #247, which I authored and opened on July 22. The code is substantially identical — ~95% of the non-empty lines in converters/gsf/src/ossie_gsf/converter.py here match #247 verbatim — but the commit is authored under a different name, so the history doesn't reflect the original authorship.

There's also a correctness problem. This copy is based on #247 as of commit 21aa2d3. That revision targeted a provisional GSF document shape predating GSF's actual interchange format. #247 has since been updated (791b440) to emit GSF's real GsfModelDocument contract, verified by importing the converter's output into a running GSF instance. As written, this PR would ship a GSF converter whose output GSF cannot import.

The CI workflow and regression tests added here are useful, and I'm happy to incorporate that idea into #247 with attribution.

I'd ask that this be closed in favor of #247.

Thanks for clarifying the history and for updating #247 to the current GSF interchange contract (GsfModelDocument). I agree that #247 is the appropriate place to continue this work, so I'll close #275.

If helpful, I'm happy to coordinate the CI and test improvements through #247 with clear attribution.