1. Proposed title of this feature request.
Param Enum - Implementation

2. What is the nature and description of the request?

Client is requesting for the pipeline input options to  have a input param type other than text box like a drop down or check box or dynamic input which is standard in other pipelines.
A Task Author should be able to specify a list of allowed values for the param.

3. Why does the customer need this? (List the business requirements here)
Limitation in automation via tekton pipelines. Task can be simplified in clients CI. 
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4. Additional Details:
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OCP: 4.12 
Pipelines operator: 1.11

Ongoing Upstream issue:

https://github.com/tektoncd/pipeline/issues/7410