Enable packaging and test workflows to be triggered mannually with custom inputs

[ValentinBuira]

This PR enable a workflow to be triggered manually with custom inputs using workflow_dispatch event. The packages.yml and run-test.yml workflow are currently supported

This PR reuse the same workflow used when a commit is pushed and should remain compatible

Currently we support the following argument(inputs)

• PYTHON_API_CLIENT_VER : For python-api-client you can choice any release, tag or branch
• GEODIFF_VER: For geodiff only the version uploaded on PyPi are supported

To note, you can't trigger the workflow from the github web interface since it's not yet on the default branch, to test from the cli interface, use the following command e.g:

For packaging:

gh workflow run "Build Mergin Plugin Packages" --ref workflow-dispatch -f PYTHON_API_CLIENT_VER="master"

For test:

gh workflow run "Run Mergin Plugin Tests" --ref workflow-dispatch -f PYTHON_API_CLIENT_VER="project-history"

[tomasMizera]

Thanks for the adjustments!