Unified Storage: Adds pruner to kv backend (#110549)

* WIP adding pruner to kv store impl

* pruner only keeps 20 most recent versions

* ignore grafana-kv-data folder

* extracts some stuff to pruner.go file. Adds tests. Adds kvBackendOptions.

* update logging, comments, exports kvbackendoptions fields

* update nooppruner ref

* fixes field casing in test

* fix test

* linter fixes

* remove comment

* make KvStorageBackend private

* Adds pruner key validation and tests. Fixes broken tests.

* update error message when validating pruner key

pkg/storage/unified/resource/pruner_test.go

@@ -0,0 +1,67 @@
+package resource
+
+import "testing"
+
+func TestPrunerValidate(t *testing.T) {
+	tests := []struct {
+		name     string
+		key      PruningKey
+		expected bool
+	}{
+		{
+			name: "valid key",
+			key: PruningKey{
+				Namespace: "default",
+				Group:     "apps",
+				Resource:  "deployments",
+				Name:      "my-deployment",
+			},
+			expected: true,
+		},
+		{
+			name: "missing namespace",
+			key: PruningKey{
+				Group:    "apps",
+				Resource: "deployments",
+				Name:     "my-deployment",
+			},
+			expected: false,
+		},
+		{
+			name: "missing group",
+			key: PruningKey{
+				Namespace: "default",
+				Resource:  "deployments",
+				Name:      "my-deployment",
+			},
+			expected: false,
+		},
+		{
+			name: "missing resource",
+			key: PruningKey{
+				Namespace: "default",
+				Group:     "apps",
+				Name:      "my-deployment",
+			},
+			expected: false,
+		},
+		{
+			name: "missing name",
+			key: PruningKey{
+				Namespace: "default",
+				Group:     "apps",
+				Resource:  "deployments",
+			},
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := tt.key.Validate()
+			if result != tt.expected {
+				t.Errorf("expected %v, got %v", tt.expected, result)
+			}
+		})
+	}
+}