Loki: Add support for distinct operation in autocomplete and query builder (#69003)

* Loki Autocomplete: add support for suggesting distinct

* Loki query builder: add distinct as format operation

* Remove unused import

* Loki visual query: add support to parse distinct filters

* Query builder: use label param editor for distinct

* Loki Autocomplete: Improve distinct label suggestions

* Query Builder: improve distinct parsing

* Fix tests

* Update tests

public/app/plugins/datasource/loki/querybuilder/parsing.test.ts

@@ -716,6 +716,36 @@ describe('buildVisualQueryFromString', () => {
       },
     });
   });
+
+  it('parses a log query with distinct and no labels', () => {
+    expect(buildVisualQueryFromString('{app="frontend"} | distinct')).toEqual(
+      noErrors({
+        labels: [
+          {
+            op: '=',
+            value: 'frontend',
+            label: 'app',
+          },
+        ],
+        operations: [{ id: LokiOperationId.Distinct, params: [] }],
+      })
+    );
+  });
+
+  it('parses a log query with distinct and labels', () => {
+    expect(buildVisualQueryFromString('{app="frontend"} | distinct id, email')).toEqual(
+      noErrors({
+        labels: [
+          {
+            op: '=',
+            value: 'frontend',
+            label: 'app',
+          },
+        ],
+        operations: [{ id: LokiOperationId.Distinct, params: ['id', 'email'] }],
+      })
+    );
+  });
 });
 
 function noErrors(query: LokiVisualQuery) {