Add mutex lock in repository saves

[gringolito]

Concurrent saves were overwriting due to racing conditions on file reads/writes. To avoid those race conditions a R/W mutex was added into the host.Repository implementation to sequentiate the concurrent writes on the filesystem.

Also, some improvements to the logging system were made to help debug the issue, such as adopting (ordered) UUIDv7 on the RequestId instead of the previously used UUIDv4.

[codecov]

Codecov Report

Attention: Patch coverage is 84.37500% with 5 lines in your changes missing coverage. Please review.

Project coverage is 71.84%. Comparing base (477fd9e) to head (b9fd3b9).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
api/middleware.go	70.00%	2 Missing and 1 partial ⚠️
api/middleware/fiberslog/slog.go	0.00%	2 Missing ⚠️

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
- Coverage   72.76%   71.84%   -0.92%     
==========================================
  Files          20       20              
  Lines         804      984     +180     
==========================================
+ Hits          585      707     +122     
- Misses        206      263      +57     
- Partials       13       14       +1     

Files with missing lines	Coverage Δ
pkg/host/repository.go	97.70% <100.00%> (+0.83%)	⬆️
api/middleware/fiberslog/slog.go	0.00% <0.00%> (ø)
api/middleware.go	69.23% <70.00%> (-2.20%)	⬇️

... and 16 files with indirect coverage changes