Added suite.metadata property and to_latex helper and tests (fixes #1126)

[anvithagowda098]

What does the PR fix?

This PR implements the OpenMLBenchmarkSuite.metadata property and the suite.to_latex(...) helper method. This essentially fixes #1126

What this adds

• suite.metadata
  Returns a pandas DataFrame with:

  • dataset IDs,
  • task IDs,
  • dataset names,
  • #instances (n), #features (p), #classes (C)

• suite.to_latex(filename, caption=None, label=None)
  A lightweight, non-opinionated LaTeX export helper for the metadata.
  It:

  • prefers pandas Styler formatting if jinja2 is installed,
  • otherwise falls back to a minimal internal LaTeX generator,
  • never imposes formatting rules/tricks on the user.

Why

Per discussion in #1126, maintainers preferred exposing the DataFrame (suite.metadata) instead of an opinionated Latex formatter. This PR:

• provides the canonical DataFrame for suites,
• includes a small, non-opinionated to_latex convenience helper,
• ships tests (mocked + server-tagged).

Notes

• The to_latex helper will prefer pandas' Styler when jinja2 is available; otherwise it uses a small fallback generator that does not require extra dependencies.
• The server integration test will skip if suite 99 is not present on the configured server.
• Additionally, if the fix is satisfactory, examples and a mention of the same in documentation can be done.

Metadata

• Reference Issue: Fixes #1126
• New Tests Added: Yes
• Documentation Updated: No