Adopt AIP-0203: Field Behavior

[rambleraptor]

Fixes #29

Proto changes in aep-dev/aep-components#13

It's unclear to me if we need an OpenAPI extension, but I'd guess we do?

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[toumorokoshi]

It's unclear to me if we need an OpenAPI extension, but I'd guess we do?

We definitely need OpenAPI variants - I'll file an issue at least.

[toumorokoshi]

Thanks! A few notes on this one - really on issues in the existing AIPs*.

[toumorokoshi]

One last nit, but otherwise LGTM! I'm approving assuming you'll address the one comment, but will hopefully save you the cycle time on approval.

Thanks!

[mkistler]

Need to change "name" to "path" in a bunch of places (I think I caught them all).

After that I think we should merge this. I think this AEP will require extensive changes to generalize the guidance and then add OAS-specifics, so we should do that in a separate PR.

[mkistler]

Two more minor fixes, but I'll approve as these are straightforward.