Fix concurrent map read/write panic in configuration map

[nitishagar]

What

Make internal/go-configmap.Map safe for concurrent use with a sync.RWMutex.

Why

The background "check for updates" goroutine started for every command reads the settings map (shouldCheckForUpdate → GetBool) while config set concurrently writes and YAML-marshals the same map. This races the underlying Go map and panics with fatal error: concurrent map read and map write (reported on Windows CI in #3103).

How

• Add a pointer *sync.RWMutex to Map (a value mutex would be copied by the value-receiver methods and protect nothing) and initialize it in New().
• Lock at the exported entry points (Get/Set/Delete/Merge/AllKeys/Schema/SetKeyTypeSchema/Marshal*/Unmarshal* and the cli.go setters); keep the recursive helpers lock-free so the top-level lock protects the whole nested tree without deadlocking.
• MarshalYAML/MarshalJSON return a deep snapshot so the encoder never iterates the live map after the lock is released.
• Add TestConcurrentAccess (concurrent reader + writer + marshal), which fails under -race without the fix.

Fixes #3103

[CLAassistant]

All committers have signed the CLA.

[nitishagar]

The only failing check here is test-integration (windows-latest, monitor), which looks like an unrelated flaky test rather than a problem with this change. The monitor integration group also flaked (on macOS) on my unrelated PR #3217, which doesn't touch this code at all, and the latest master integration run passes it.

This change only adds a sync.RWMutex to internal/go-configmap, and the new -race regression test (TestConcurrentAccess) passes locally and in CI. Could a maintainer re-run the failed job when convenient? Happy to rebase or adjust if anything is needed. Thanks!

[codecov]

Codecov Report

❌ Patch coverage is 92.30769% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.49%. Comparing base (f9fd5c7) to head (0befe04).

Files with missing lines	Patch %	Lines
internal/go-configmap/cli.go	75.00%	3 Missing ⚠️
internal/go-configmap/configuration.go	94.87%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3216      +/-   ##
==========================================
+ Coverage   69.43%   69.49%   +0.06%     
==========================================
  Files         252      252              
  Lines       19595    19641      +46     
==========================================
+ Hits        13606    13650      +44     
- Misses       4718     4719       +1     
- Partials     1271     1272       +1     

Flag	Coverage Δ
unit	69.49% <92.30%> (+0.06%)	⬆️

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