New workflow to validate Tekton definitions

[durera]

Feature and motivation

New workflow ( only on PR to master):

• log in to masdeps2
• create branch named with the pr number
• install the ibm-mas-tekton and ibm-mas-tekton-fvt yaml files, fail on error
• delete the namespace

This only runs on a PR to master as we don't want to overload masdeps2 with work, this is a heathy balance between benefit of this test and cost incurred.

Usage example

This will help avoid issues like that fixed in https://github.com/ibm-mas/cli/pull/1182 as we will catch them in the status checks on the PR.