Update types to fix API review feedback

[youngnick]

/kind cleanup

What this PR does / why we need it:

• Adds the Programmed Condition to the Gateway default condition list. (API Review for v0.6.0 release #1538 (comment))
• Adds conformance information to all the type selectors that have values like Exact and RegularExpression to ensure that RegularExpression is clearly ImplementationSpecific conformance. (Conformance levels of match types not clearly documented in GRPCRoute and HTTPRoute #1581)

Which issue(s) this PR fixes:
Fixes #1581

Does this PR introduce a user-facing change?:

- The Gateway default conditions list now includes the Programmed condition.
- `RegularExpression` type selectors have been clarified to all be `ImplementationSpecific` conformance.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: youngnick

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [youngnick]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[robscott]

Thanks @youngnick!

/lgtm