feat(policy-devel): drop support for yaml and embedded rego formatting

[Piskoo]

This PR removes support for yaml and embedded rego formatting due issues caused by yaml libraries limitations.

Closes #2379

[migmartri]

@Piskoo do we still check that the policy is a valid policy spec? Meaning that we can marshal it?

[Piskoo]

@migmartri Only for eval, the only operation that lint does on yaml files is lookup for rego script paths

[migmartri]

@migmartri Only for eval, the only operation that lint does on yaml files is lookup for rego script paths

there might be value on still checking that it's a valid policy spec no? Before we used to run even proto validations on the spec no?

[Piskoo]

@migmartri Only for eval, the only operation that lint does on yaml files is lookup for rego script paths

there might be value on still checking that it's a valid policy spec no? Before we used to run even proto validations on the spec no?

Correct, took a look and validations are still ran on policy spec but errors are ignored. I'll fix it in another PR