rofl-appd: Add upsert and delete metadata endpoint

[matevz]

Implements #2405

[netlify]

✅ Deploy Preview for oasisprotocol-oasis-sdk canceled.

Name	Link
🔨 Latest commit	bd64052
🔍 Latest deploy log	https://app.netlify.com/projects/oasisprotocol-oasis-sdk/deploys/6a3e624943da6c0008fd8e2d

[codecov]

Codecov Report

❌ Patch coverage is 0% with 46 lines in your changes missing coverage. Please review.
✅ Project coverage is 51.18%. Comparing base (3e00a16) to head (bd64052).

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%   51.18%   -0.12%     
==========================================
  Files         237      237              
  Lines       17236    17279      +43     
==========================================
+ Hits         8842     8844       +2     
- Misses       8334     8375      +41     
  Partials       60       60              

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[matevz]

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

Discussion: time-rs/time#783

[matevz]

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

Discussion: time-rs/time#783

Time crate 0.3.51 compiles fine. Unblocking.

[matevz]

I tested the new PUT and DELETE methods and work as expected.