Patch strategy support

[clux]

Currently Api::patch and similar only support --type=merge (i.e. .header("Content-Type", "application/merge-patch+json")).

Would be good to support the 3 strategies.

Note that CRDs doesn't seem to support strategic merge atm, so need better tests. See kubernetes/kubernetes#52772.

[ragne]

Hi, I'd like to tackle on the issue. How resulting api should look like?

• The simple idea is to add another parameter (enum) to Api::patch but it doesn't sound that great, though.
• Second one is to add that parameter to PostParams (create another struct PatchParams?) and check in Api::patch like it was done for dry_run?

[clux]

Hey, awesome! Please go right ahead.

I totally agree with the PatchParams, it's already close to what's in kubernetes under meta/v1#PatchOptions.

[clux]

Funnily enough though, client-go still passes in an enum and a PatchOptions object 😕
https://github.com/kubernetes/client-go/blob/e6a502f77fded2b9d038629506553ae5bb6e0388/dynamic/client_test.go#L641