fix: Use mutex when modifying state using snap_setState

[FrederikBolding]

Adds a mutex per Snap that can be used to make usage of snap_setState in parallel more safe. The assumption was that this was already safe since getting and setting the state nearly always is a synchronous task. However, in practice, at least on mobile, this assumption has been proven false. This change may include a performance penalty, but it is important for snap_setState to be safe to use without data loss.

---

Note

Wraps snap_setState in a per-Snap mutex to safely handle parallel state updates and adds tests; updates deps and minor coverage thresholds.

• snaps-rpc-methods:
  • State updates: Wrap snap_setState logic in a per-Snap async-mutex (getMutex, mutexes map, runExclusive) to serialize concurrent updates.
  • Types: Use SnapId for mutex keying.
  • Tests: Add concurrency test ensuring mutex serializes updates; adjust imports to use createDeferredPromise.
  • Dependencies: Add async-mutex.
  • Config: Slightly adjust Jest coverage thresholds.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.28%. Comparing base (7ad4e66) to head (358aad0).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3742   +/-   ##
=======================================
  Coverage   98.28%   98.28%           
=======================================
  Files         418      418           
  Lines       12175    12184    +9     
  Branches     1886     1887    +1     
=======================================
+ Hits        11966    11975    +9     
  Misses        209      209           

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