refactor: Migrate gcs cache to opendal based

[Xuanwo]

Signed-off-by: Xuanwo github@xuanwo.io

This PR will introduce the following user face changes:

• Add fully Google ADC support
• Add SCCACHE_GCS_SERVICE_ACCOUNT to allow the user to specify the service account to fetch tokens from VM metadata.
• Deprecate SCCACHE_GCS_CREDENTIALS_URL and SCCACHE_GCS_OAUTH_URL; hence we will build the correct URL via the service account instead.

And, yes, remove a lot of code 🚀

[codecov-commenter]

Codecov Report

Base: 29.86% // Head: 29.98% // Increases project coverage by +0.12% 🎉

Coverage data is based on head (3a4b60b) compared to base (416c96c).
Patch coverage: 37.83% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1474      +/-   ##
==========================================
+ Coverage   29.86%   29.98%   +0.12%     
==========================================
  Files          47       47              
  Lines       16974    16572     -402     
  Branches     8056     7827     -229     
==========================================
- Hits         5069     4969     -100     
+ Misses       6503     6349     -154     
+ Partials     5402     5254     -148     

Impacted Files	Coverage Δ
src/util.rs	34.53% <ø> (-0.78%)	⬇️
tests/sccache_cargo.rs	32.55% <ø> (+0.91%)	⬆️
src/cache/gcs.rs	29.41% <25.00%> (+8.96%)	⬆️
src/config.rs	35.81% <26.31%> (-0.75%)	⬇️
src/cache/cache.rs	35.29% <100.00%> (-0.71%)	⬇️
src/cache/disk.rs	35.61% <0.00%> (-1.37%)	⬇️
src/server.rs	31.67% <0.00%> (-0.43%)	⬇️
src/lib.rs	8.47% <0.00%> (-0.38%)	⬇️
src/compiler/c.rs	38.53% <0.00%> (-0.23%)	⬇️
... and 10 more

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