Add acquireLock, releaseLock. Fix metadata for multiple queues

[adam-fowler]

• Moved metadata setup to separate migration.
• Renamed metadata table to swift_jobs.metadata

[codecov]

Codecov Report

Attention: Patch coverage is 97.43590% with 2 lines in your changes missing coverage. Please review.

Project coverage is 91.02%. Comparing base (489e671) to head (dc9d6d6).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...stgres/Migrations/CreateJobMetadataMigration.swift	95.83%	1 Missing ⚠️
Sources/JobsPostgres/PostgresJobsQueue.swift	98.14%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #39      +/-   ##
==========================================
+ Coverage   90.56%   91.02%   +0.45%     
==========================================
  Files           7        8       +1     
  Lines         530      568      +38     
==========================================
+ Hits          480      517      +37     
- Misses         50       51       +1     

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[thoven87]

looks good. It's very flexible as one can have one schedule per queue. Usually, we just need one