Pipelines as Code: Allow having pipelines in .tekton sub directories

As a user of a team contributing with other teams in a mono repo environment I want to be able to have all my pipelines in a sub directory of the .tekton/ directory and not interfere with the other teams.

Details:

• We can just do the same mechanism as what we do to get all yaml files in .tekton/ via the VCS API but instead if we see a dir in there we can recurse ourselves to traverse this directory and grab all yaml files in there.
• maybe we should think about conflict, if there is is a task named buildah in subdir foo/ and a task named buildah in bar/ what would happen ? this same applies where multiple yaml files have the same name too on the top dir (i think last one win currently)