provider/tekton: add tangled metadata as params
This allows you to do tests against the individual commit being operated
against instead of just the most recent commit on HEAD. These are a
no-op when pipelines do not use these parameters.
Example usage:
```yaml
steps:
- name: git-clone
image: reg.xeiaso.net/xe/x/git:latest
script: |
set -euo pipefail
git clone $(params.url) /workspace/repo-data/repo
cd /workspace/repo-data/repo
git checkout $(params.commit)
```
Signed-off-by: Xe Iaso <me@xeiaso.net>