[TEP-0131] Update Conformance Spec for v1 api types

This commit updates the initial api spec from TEP-012 with changes from the
conformance policy defined in TEP-131 including:

- Using v1 resources instead of v1beta1 types
- Conformance specs for Tasks, Pipelines and PipelineRuns in addition to TaskRun
- Removes HTTP API requirement from conformance spec, instead the spec is defined in terms of JSON/YAML resources that can be consumed via an API
- The RECOMMENDED profile now includes support for taskRefs and pipelineRefs

Signed-off-by: Dibyo Mukherjee <[email protected]>