Chore: SQL store split for annotations (#55089)

* Chore: SQL store split for annotations

* Apply suggestion from code review

pkg/services/annotations/annotationstest/fake.go

@@ -0,0 +1,83 @@
+package annotationstest
+
+import (
+	"context"
+	"sync"
+
+	"github.com/grafana/grafana/pkg/services/annotations"
+)
+
+type fakeAnnotationsRepo struct {
+	mtx         sync.Mutex
+	annotations map[int64]annotations.Item
+}
+
+func NewFakeAnnotationsRepo() *fakeAnnotationsRepo {
+	return &fakeAnnotationsRepo{
+		annotations: map[int64]annotations.Item{},
+	}
+}
+
+func (repo *fakeAnnotationsRepo) Delete(_ context.Context, params *annotations.DeleteParams) error {
+	repo.mtx.Lock()
+	defer repo.mtx.Unlock()
+
+	if params.Id != 0 {
+		delete(repo.annotations, params.Id)
+	} else {
+		for _, v := range repo.annotations {
+			if params.DashboardId == v.DashboardId && params.PanelId == v.PanelId {
+				delete(repo.annotations, v.Id)
+			}
+		}
+	}
+
+	return nil
+}
+
+func (repo *fakeAnnotationsRepo) Save(ctx context.Context, item *annotations.Item) error {
+	repo.mtx.Lock()
+	defer repo.mtx.Unlock()
+
+	if item.Id == 0 {
+		item.Id = int64(len(repo.annotations) + 1)
+	}
+	repo.annotations[item.Id] = *item
+	return nil
+}
+
+func (repo *fakeAnnotationsRepo) Update(_ context.Context, item *annotations.Item) error {
+	return nil
+}
+
+func (repo *fakeAnnotationsRepo) Find(_ context.Context, query *annotations.ItemQuery) ([]*annotations.ItemDTO, error) {
+	repo.mtx.Lock()
+	defer repo.mtx.Unlock()
+
+	if annotation, has := repo.annotations[query.AnnotationId]; has {
+		return []*annotations.ItemDTO{{Id: annotation.Id, DashboardId: annotation.DashboardId}}, nil
+	}
+	annotations := []*annotations.ItemDTO{{Id: 1, DashboardId: 0}}
+	return annotations, nil
+}
+
+func (repo *fakeAnnotationsRepo) FindTags(_ context.Context, query *annotations.TagsQuery) (annotations.FindTagsResult, error) {
+	result := annotations.FindTagsResult{
+		Tags: []*annotations.TagsDTO{},
+	}
+	return result, nil
+}
+
+func (repo *fakeAnnotationsRepo) Len() int {
+	repo.mtx.Lock()
+	defer repo.mtx.Unlock()
+
+	return len(repo.annotations)
+}
+
+func (repo *fakeAnnotationsRepo) Items() map[int64]annotations.Item {
+	repo.mtx.Lock()
+	defer repo.mtx.Unlock()
+
+	return repo.annotations
+}