chore: add swap endpoint interface for sol vault swaps

[albert-llimos]

Pull Request

Checklist

Please conduct a thorough self-review before opening the PR.

• [x] I am confident that the code works.
• [ ] I have written sufficient tests.
• [ ] I have written and tested required migrations.
• [ ] I have updated documentation where appropriate.

Summary

This is necessary for the broker api Solana Vault swaps encoding. I am adding it now for @syan095 to work on it.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 71%. Comparing base (d4f68cc) to head (8cff95c). Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
...chains/src/sol/sol_tx_core/program_instructions.rs	0%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #5459 +/- ## ====================================== - Coverage 71% 71% -0% ====================================== Files 494 494 Lines 87666 87544 -122 Branches 87666 87544 -122 ====================================== - Hits 62674 62494 -180 - Misses 22381 22437 +56 - Partials 2611 2613 +2 ```

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