fix(tests): changed the expexted format of the config files

[rostalan]

• https://issues.redhat.com/browse/RHIDP-9524
• updated the integration tests to reflect changes in workspaces/<workspace_name>/metadata/<plugin_name>.yaml file format.
• added env var file (workspaces/<workspace_name>/tests/test.env) checks, it passes if the file is found and contains all needed vars, skips when no file is found and required and fails if any of the required vars are missing.
• updated README.md

[davidfestal]

Do you really need to install yq with:

      - name: Setup yq
        uses: mikefarah/yq@v4

knowing that it is included by default in the ubuntu runner (afaict) ?

[rostalan]

/publish

[github-actions]

PR action (/publish) cancelled: PR doesn't touch only 1 workspace.