Teach codegen to accept and generate additionalPrinterColumns

[bcotton]

This will get passed through to the CRDs.

I don't know how to get the thema tests to pass. Ideas?

customKind.lineage.schemas.1.additionalPrinterColumns: field not allowed:
    /github.com/grafana/grafana-app-sdk/codegen/thema/testing/customkind.cue:69:13
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:42:24
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:42:27
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:45:2
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:46:34
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:46:37
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:46:38
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:231:13
    /github.com/grafana/grafana-app-sdk/kindsys/kindcat_custom.cue:115:2
    /github.com/grafana/grafana-app-sdk/kindsys/kindcats.cue:69:11
customKind.lineage._sortedSchemas: invalid value [] (does not satisfy list.MinItems(1)): len(list) < MinItems(1) (0 < 1):
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:98:7
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:94:21
    /github.com/grafana/grafana-app-sdk/kindsys/cue.mod/pkg/github.com/grafana/thema/lineage.cue:98:21
--- FAIL: TestCRDGenerator (0.14s)
    --- FAIL: TestCRDGenerator/JSON (0.04s)
        generators_test.go:34:
                Error Trace:    /Users/bcotton/projects/grafana-app-sdk/codegen/thema/generators_test.go:34

[radiohead]

Looks good!

I'll leave it up to @IfSentient to look into Thema tests – perhaps it's time to drop our support for it.

[IfSentient]

LGTM except for one minor change in the CUE.