Track corpus

[frankeld]

Summary

• Tracks corpus file
  • Reasoning: Downstream, ocaml-tree-sitter assumes that corpus tests have been committed to the tree-sitter repo. To test against regressions, it symlinks and runs the tests. See https://github.com/returntocorp/ocaml-tree-sitter-semgrep/blob/cabfe800af79188f69bd7b4380cf54274f6db790/lang/semgrep-grammars/src/prep.common#L27-L36. We want these tests to run.
• Ensures build files are up to date in PRs
  • Reasoning: Will catch any corpus or tree-sitter gen discrepancies

To verify that action is working, reference purposefully failed actions below in 45633b0 (see https://github.com/slackhq/tree-sitter-hack/runs/3284730037).

Requirements (place an x in each [ ])

• [x] I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• [x] I've read and agree to the Code of Conduct.