Design and implement task results in final tasks

[pritidesai]

finally at the pipeline level is on its way:

design doc
PR - which will be split into multiple PRs

First iteration of final tasks are implemented without task results and from clause for Pipeline Resources. In next iteration, please finalize the design for adding support for task results.

Reference:

• WIP - implementing finally at the pipeline level 🤞🏼💥😱 #2437 (comment)

• "Finally" tasks for Pipeline #2446 (Implement finally at the pipeline level)

• Design: Failure Strategy for TaskRuns in a PipelineRun #1684 (part of designing failure strategy for taskrun in a pipeline)

[vdemeester]

/kind feature

[pritidesai]

/assign