ci: share sccache setup across workflows

[abnobdoss]

What

Add two composite actions for sccache:

• .github/actions/setup-sccache sets the sccache environment, restores the cache, resolves the MSVC compiler version on Windows, and starts mozilla-actions/sccache-action.
• .github/actions/save-sccache shows sccache stats for every run and saves the cache only on main branch runs.

The Test, SQL Catalog, sanitizer, C++ linter, and AWS workflows now pass only their cache key prefix at each call site.

This is part of the CI work discussed in #799.

Notes

The existing cache key shapes are preserved for the current CMake workflow legs. The Meson Windows leg now also gets the MSVC-version key suffix, matching the other Windows sccache legs and avoids cache misses after runner image compiler updates.

The MSVC version source also changes for the existing Windows legs (test and SQL catalog): the inline cl.exe banner parse is replaced by reading VCToolsVersion.default.txt via vswhere, which is more reliable and does not require cl.exe on PATH. This produces a different version format (e.g. 14.44.35217 vs 19.44.35217.1), so all Windows caches will miss once and reseed on the first post-merge main run.

Third-party actions stay pinned inside composite action.yml files, which are covered by the ASF allowlist checker glob.

Validation

• Validated builds in fork: Test, AWS, SQL Catalog, ASAN/UBSAN, and pre-commit.
• The C++ linter workflow ignores .github/**, so this PR does not exercise that workflow until a source-touching run or post-merge.