add wasm functionality to apply-setters and rewrite to new go kpt fn sdk

[wmuizelaar]

Just like #911 - this adds wasm functionality to apply-setters. As discussed during the latest office-hours I also attempted to port the functionality to the new SDK.

Please review thoroughly and share feedback - I tried to keep as much of the old code in place as possible, but I wasn't able to properly read the 'old' ConfigMap configuration structure, so had to craft a new config format - which is obviously a breaking change. I'm not too happy with that, so ideas on how to prevent that are appreciated ;-)

[yuwenma]

Hi, @wmuizelaar, thank you for the contribution.

We do not want to add new features to the apply-setter functions, as explained in kptdev/kpt#3131. For your use cases, I'd recommend using apply-replacements function instead as we talked about in the office hour. I understand the apply-replacement may not be sufficient enough from the feasibility and maintenance perspective. If that's the case, do you mind sharing your examples in kptdev/kpt#3131 so we can evaluate and further help.