chore(ci): add rust dependency caching with rust-cache action

[K-dash]

Description

I made some changes to reduce the ci.yml time for Rust tests.

Closes #218

How are the changes test-covered

• N/A
• Automated tests (unit and/or integration tests)
• Manual tests
  • Details are described below

The changes made are as follows:

1. Added the Swatinem/rust-cache action.
   This allows us to cache dependencies and build artifacts so repeated builds can skip redownloading or recompiling crates that are unchanged.

2. Added the --skip-clean argument to tarpaulin.
   By default, tarpaulin behaves as if --force-clean is set, which deletes existing build artifacts and prevents reuse of cached builds.
   With --skip-clean, the cached artifacts from Swatinem/rust-cache can be used before running tests.
   (See Tarpaulin documentation on recompilation for details.)

Below are some CI logs from my fork that demonstrate how the caching works under different conditions:

• First CI run
  Full build is required since there is no cache yet.
  Once complete, a cache is stored.
  1. Link to the GitHub Actions log

• Second CI run (minor code changes in crates/core/src/config/error.rs but no new dependencies)
  We only added a comment in the source code, so no dependencies were modified.
  This means the cached artifacts are still valid and the test build is fast.
  2. Link to the GitHub Actions log

• Third CI run (added a new dependency in python/Cargo.toml)
  The python crate is rebuilt, but other crates (core, hudi, etc.) remain cached.
  3. Link to the GitHub Actions log

Please review these changes and let me know if you have any questions.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.26%. Comparing base (04fe00d) to head (4ae1e7b).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #265      +/-   ##
==========================================
+ Coverage   91.20%   91.26%   +0.06%     
==========================================
  Files          40       41       +1     
  Lines        1967     2015      +48     
==========================================
+ Hits         1794     1839      +45     
- Misses        173      176       +3     

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[xushiyan]

LGTM!