PipelineRef resolver part doesn't support context variable replacement

[vdemeester]

Expected Behavior

Using the following PipelineRun should create the following ResolutionRequest.

apiVersion: tekton.dev/v1beta1
kind: PipelineRun
metadata:
  name: simple-pipelinerun
spec:
  pipelineRef:
    resolver: foo
    params:
    - name: bar
      value: $(context.pipelinerun.name)
---
apiVersion: resolution.tekton.dev/v1alpha1
kind: ResolutionRequest
metadata:
  labels:
    resolution.tekton.dev/type: foo
  name: foo-bf6f3d56876eb1d6948a50c52c0d1d87
spec:
  params:
    bar: simple-pipelinerun

Actual Behavior

It doesn't resolve the context.* variable, resulting in the following ResolutionRequest.

apiVersion: resolution.tekton.dev/v1alpha1
kind: ResolutionRequest
metadata:
  labels:
    resolution.tekton.dev/type: foo
  name: foo-bf6f3d56876eb1d6948a50c52c0d1d87
spec:
  params:
    bar: $(context.pipelinerun.name)

Steps to Reproduce the Problem

1. Create the above PipelineRun
2. See what ResolutionRequest it creates

Additional Info

• Tekton Pipeline version: main

/assign @abayer