Add batched and extra params settings for the extension

[ThisCakeIsALie]

This PR adds new settings for features that were recently (or not so recently) added to the CLI:

• Source file encoding control: Provides an overwrite for the encoding Reqs2X uses by default when reading tests and source files (releveant for code with non-English scripts such as Chinese or Korean)
• Extra parameters for model requests: Necessary to regulate thinking models and deal with other provider-specific oddities
• Batched mode: Has existed for a long time, however has not been configurable via the extension so far

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.70%. Comparing base (f099676) to head (b5795b7).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #332   +/-   ##
=======================================
  Coverage   96.70%   96.70%           
=======================================
  Files           9        9           
  Lines        1729     1729           
  Branches      194      194           
=======================================
  Hits         1672     1672           
  Misses         57       57           

Flag	Coverage Δ
Unit	96.70% <ø> (ø)

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud