PROCESS CHANGE: Merge Client and Functions WG together

Things to include with your process proposal (delete this text):

* Expected benefits. Who gains the benefits? Why will they benefit?

Both Client WG and Functions WG represent a portion of Knative CLI. They are designed with different use cases in mind, but under the hood it's a terminal API.

Currently, there's no high demand or interest in Client WG from both users and contributors POV.

We have had a conversion wrt/ this proposal during previous TOC reviews, and as a part of community health discussion.

* Expected costs. Who bears the costs? How heavy are they?

Less WG calls, in addition joint WG update.

* Timeframe for implementation / rollout.

Week to sync WG calls and make announcements on channels, mailing list etc.

* Are you willing to drive the process, or is this a request for help?

Yes

Finally, I'd like to ask you all to vote for the name of this joint WG. @rhuss mentioned it would be great to keep `Functions` on top level rather than wrapping it under e.g. `CLI WG`. Please use thumb up on the comments below. Feel free to propose any suggestion that might be interesting.

New WG name proposals:

- `Functions & Client Working Group`
- `Functions & CLI Working Group`
- `CLI Working Group`

/cc @lkingland @rhuss
/cc @knative/technical-oversight-committee
/cc @knative/steering-committee