Generate Swift mocks by building local RustSDK

[nimau]

This PR:

• updates the BuildSDK.swift tool to build Swift mocks when building locally the SDK
• adds some unit tests for ClientProxy using generated mocks.

GH Issue: #2266

‼️ This PR depends on:

• uniffi-rs PR: PR adding Swift mock generation to uniffi
• matrix-rust-sdk PR: PR adding Swift mock generation

In the meantime, it can be tested locally by modifying matrix-rust-sdk/Cargo.toml as described here and by generating a local sdk using: swift run tools build-sdk

[sonarcloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

4 New issues
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

	Warnings
⚠️	Please add a changelog.
⚠️	Some of the commits are missing ticket numbers. Please consider squashing all commits that don't have a tracking number.

Generated by 🚫 Danger Swift against a314f1d

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f844cd1) 72.39% compared to head (a314f1d) 72.38%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2290      +/-   ##
===========================================
- Coverage    72.39%   72.38%   -0.01%     
===========================================
  Files          512      512              
  Lines        35273    35273              
  Branches     16969    16969              
===========================================
- Hits         25536    25534       -2     
  Misses        9108     9108              
- Partials       629      631       +2     

Flag	Coverage Δ
unittests	58.03% <ø> (-0.11%)	⬇️

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