Thread safety

[kawoou]

Results tried a simple test, I found that not thread safety.
Therefore, I changed Mutex to NSRecursiveLock and increased the lock coverage.

[codecov-io]

Codecov Report

Merging #30 into develop will decrease coverage by 0.79%.
The diff coverage is 85.5%.

@@            Coverage Diff             @@
##           develop      #30     +/-   ##
==========================================
- Coverage    66.36%   65.57%   -0.8%     
==========================================
  Files           17       16      -1     
  Lines          559      549     -10     
==========================================
- Hits           371      360     -11     
- Misses         188      189      +1

Impacted Files	Coverage Δ
Sources/Deli/Core/Container.swift	69.15% <76.92%> (-2.54%)	⬇️
Sources/Deli/Core/AppContext.swift	96.87% <96.66%> (+0.13%)	⬆️

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