rofl-appd: Add upsert and delete metadata endpoint

[matevz]

Implements #2405

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 46 lines in your changes missing coverage. Please review.
✅ Project coverage is 51.23%. Comparing base (3e00a16) to head (d885e48).

Files with missing lines	Patch %	Lines
rofl-appd/src/services/metadata.rs	0.00%	31 Missing ⚠️
rofl-appd/src/routes/metadata.rs	0.00%	10 Missing ⚠️
rofl-appd/src/lib.rs	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2478      +/-   ##
==========================================
- Coverage   51.29%   51.23%   -0.07%     
==========================================
  Files         237      236       -1     
  Lines       17236    17261      +25     
==========================================
+ Hits         8842     8843       +1     
- Misses       8334     8358      +24     
  Partials       60       60              

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[matevz]

Tests seem to be failing due to regression in time 0.3.48 crate released today. 😠