Add GEP describing goals for service mesh in Gateway API

[keithmattix]

Signed-off-by: Keith Mattix II [email protected]

What type of PR is this?

/kind gep

What this PR does / why we need it: This PR adds a GEP describing the high level goals for adding service mesh functionality in Gateway API as well as a glossary of terms to aid in discussion

Which issue(s) this PR fixes:

Fixes #1324

Does this PR introduce a user-facing change?:

Add GEP describing goals for service mesh in Gateway API

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: keithmattix, shaneutt

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~~ [shaneutt]

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

[keithmattix]

/assign

[youngnick]

I think this is ready for merging as provisional.

/lgtm