Introduce coremodels framework (extracted from intent-api) (#47653)

* Copy over most of coremodel from intent-api branch

* Fix import paths

* Fix incorrect provider name

* Add root compgen file, fixup componentroot.yaml

* go mod tidy

* Remove compgen for now

* Add dashboard coremodel

* Remove datasource coremodel, for now

* Tweak comments on dashboard struct model

* devenv: add dashboard testing directly

* Fixup dashboard schema for openness, heatmap

* Update Thema to tip

* Fix wire/registry references

* Fix hclog version

pkg/cuectx/ctx.go

@@ -0,0 +1,116 @@
+// Package cuectx provides a single, central CUE context (runtime) and Thema
+// library that can be used uniformly across Grafana, and related helper
+// functions for loading Thema lineages.
+
+package cuectx
+
+import (
+	"io"
+	"io/fs"
+	"path/filepath"
+	"testing/fstest"
+
+	"cuelang.org/go/cue"
+	"cuelang.org/go/cue/cuecontext"
+	"github.com/grafana/thema"
+	"github.com/grafana/thema/kernel"
+	"github.com/grafana/thema/load"
+)
+
+var ctx *cue.Context = cuecontext.New()
+var lib thema.Library = thema.NewLibrary(ctx)
+
+// ProvideCUEContext is a wire service provider of a central cue.Context.
+func ProvideCUEContext() *cue.Context {
+	return ctx
+}
+
+// ProvideThemaLibrary is a wire service provider of a central thema.Library.
+func ProvideThemaLibrary() thema.Library {
+	return lib
+}
+
+// JSONtoCUE attempts to decode the given []byte into a cue.Value, relying on
+// the central Grafana cue.Context provided in this package.
+//
+// The provided path argument determines the name given to the input bytes if
+// later CUE operations (e.g. Thema validation) produce errors related to the
+// returned cue.Value.
+//
+// This is a convenience function for one-off JSON decoding. It's wasteful to
+// call it repeatedly. Most use cases use cases should probably prefer making
+// their own Thema/CUE decoders.
+func JSONtoCUE(path string, b []byte) (cue.Value, error) {
+	return kernel.NewJSONDecoder(path)(ctx, b)
+}
+
+// LoadGrafanaInstancesWithThema loads CUE files containing a lineage
+// representing some Grafana core model schema. It is expected to be used when
+// implementing a thema.LineageFactory.
+//
+// This function primarily juggles paths to make CUE's loader happy. Provide the
+// path from the grafana root to the directory containing the lineage.cue. The
+// lineage.cue file must be the sole contents of the provided fs.FS.
+//
+// More details on underlying behavior can be found in the docs for github.com/grafana/thema/load.InstancesWithThema.
+func LoadGrafanaInstancesWithThema(
+	path string,
+	cueFS fs.FS,
+	lib thema.Library,
+	opts ...thema.BindOption,
+) (thema.Lineage, error) {
+	prefix := filepath.FromSlash(path)
+	fs, err := prefixWithGrafanaCUE(prefix, cueFS)
+	if err != nil {
+		return nil, err
+	}
+	inst, err := load.InstancesWithThema(fs, prefix)
+
+	// Need to trick loading by creating the embedded file and
+	// making it look like a module in the root dir.
+	if err != nil {
+		return nil, err
+	}
+
+	val := lib.Context().BuildInstance(inst)
+
+	lin, err := thema.BindLineage(val, lib, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	return lin, nil
+}
+
+func prefixWithGrafanaCUE(prefix string, inputfs fs.FS) (fs.FS, error) {
+	m := fstest.MapFS{
+		filepath.Join("cue.mod", "module.cue"): &fstest.MapFile{Data: []byte(`module: "github.com/grafana/grafana"`)},
+	}
+
+	prefix = filepath.FromSlash(prefix)
+	err := fs.WalkDir(inputfs, ".", (func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if d.IsDir() {
+			return nil
+		}
+
+		f, err := inputfs.Open(path)
+		if err != nil {
+			return err
+		}
+		defer f.Close() // nolint: errcheck
+
+		b, err := io.ReadAll(f)
+		if err != nil {
+			return err
+		}
+
+		m[filepath.Join(prefix, path)] = &fstest.MapFile{Data: b}
+		return nil
+	}))
+
+	return m, err
+}