[QA-1539] Add step to pick proper branch

[konrad-sol]

We need to choose proper test code branch. My proposal implemented in this PR:

• tyk-analytics repo - just do a checkout of code (github action handle tags, prs and push)
• tyk repo - we need an extra step that will choose proper branch
• pump and sink repos - extra step, but without checking tag

This new step will:

• on tag push trigger checkout the same tag (if tag was created in tyk-analytics repo, will fail otherwise - we want it to fail in this case)
• on PR it will try to checkout branch with the same name as PR branch, if not - as target branch
• on push will try to checkout target branch
  If branches are not created in tyk-analytics it will use master.