Plugins: Support for link extensions (#61663)

* added extensions to plugin.json and exposing it via frontend settings.

* added extensions to the plugin.json schema.

* changing the extensions in frontend settings to a map instead of an array.

* wip

* feat(pluginregistry): begin wiring up registry

* feat(pluginextensions): prevent duplicate links and clean up

* added test case for link extensions.

* added tests and implemented the getPluginLink function.

* wip

* feat(pluginextensions): expose plugin extension registry

* fix(pluginextensions): appease the typescript gods post rename

* renamed file and will throw error if trying to call setExtensionsRegistry if trying to call it twice.

* added reafactorings.

* fixed failing test.

* minor refactorings to make sure we only include extensions if the app is enabled.

* fixed some nits.

* Update public/app/features/plugins/extensions/registry.test.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

* Update packages/grafana-runtime/src/services/pluginExtensions/registry.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

* Update packages/grafana-runtime/src/services/pluginExtensions/registry.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

* Update public/app/features/plugins/extensions/registry.test.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

* Moved types for extensions from data to runtime.

* added a small example on how you could consume link extensions.

* renamed after feedback from levi.

* updated the plugindef.cue.

* using the generated plugin def.

* added tests for apps and extensions.

* fixed linting issues.

* wip

* wip

* wip

* wip

* test(extensions): fix up failing tests

* feat(extensions): freeze registry extension arrays, include type in registry items

* added restrictions in the pugindef cue schema.

* wip

* added required fields.

* added key to uniquely identify each item.

* test(pluginextensions): align tests with implementation

* chore(schema): refresh reference.md

---------

Co-authored-by: Jack Westbrook <jack.westbrook@gmail.com>
Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

docs/sources/developers/plugins/plugin.schema.json

@@ -463,7 +463,7 @@
     },
     "enterpriseFeatures": {
       "type": "object",
-      "description": "Grafana Enerprise specific features.",
+      "description": "Grafana Enterprise specific features.",
       "additionalProperties": true,
       "properties": {
         "healthDiagnosticsErrors": {
@@ -472,6 +472,39 @@
           "default": false
         }
       }
+    },
+    "extensions": {
+      "type": "array",
+      "description": "Extends various parts of the Grafana UI with commands or links.",
+      "items": {
+        "type": "object",
+        "description": "Expose a page link that can be used by Grafana core or other plugins to navigate users to the plugin",
+        "additionalProperties": false,
+        "required": ["type", "title", "target", "path"],
+        "properties": {
+          "type": {
+            "type": "string",
+            "enum": ["link"]
+          },
+          "title": {
+            "type": "string",
+            "minLength": 3,
+            "maxLength": 22
+          },
+          "target": {
+            "type": "string",
+            "pattern": "^(plugins|grafana)/[a-z-/0-9]*$"
+          },
+          "description": {
+            "type": "string",
+            "maxLength": 200
+          },
+          "path": {
+            "type": "string",
+            "pattern": "^/.*"
+          }
+        }
+      }
     }
   }
 }