feat: add JWT support

[shini4i]

This PR adds support for JWT as an upcoming replacement for the deploy token. It's the first step for achieving the goal stated in #288.

Currently, we support both old deploy token and JWT for adding new tasks.

[codecov]

Codecov Report

Attention: Patch coverage is 37.67123% with 91 lines in your changes are missing coverage. Please review.

Project coverage is 54.44%. Comparing base (318358a) to head (a4c0d27).

❗ Current head a4c0d27 differs from pull request most recent head 23fc008. Consider uploading reports for the commit 23fc008 to get more accurate results

Files	Patch %	Lines
cmd/argo-watcher/server/router.go	24.71%	64 Missing and 3 partials ⚠️
pkg/client/client.go	6.25%	14 Missing and 1 partial ⚠️
cmd/argo-watcher/auth/jwt.go	60.00%	4 Missing and 2 partials ⚠️
cmd/argo-watcher/server/server.go	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #299      +/-   ##
==========================================
+ Coverage   53.90%   54.44%   +0.54%     
==========================================
  Files          26       28       +2     
  Lines        1829     1899      +70     
==========================================
+ Hits          986     1034      +48     
- Misses        752      773      +21     
- Partials       91       92       +1     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarCloud