Plugins: Extend panel menu with links from plugins (#63089)

* feat(plugins): introduce dashboard panel menu placement for adding menu items

* test: add test for getPanelMenu()

* added an unique identifier for each extension.

* added context to getPluginExtensions.

* wip

* Wip

* wiwip

* Wip

* feat: WWWIIIIPPPP 🧨

* Wip

* Renamed some of the types to align a bit better.

* added limit to how many extensions a plugin can register per placement.

* decreased number of items to 2

* will trim the lenght of titles to max 25 chars.

* wrapping configure function with error handling.

* added error handling for all scenarios.

* moved extension menu items to the bottom of the more sub menu.

* added tests for configuring the title.

* minor refactorings.

* changed so you need to specify the full path in package.json.

* wip

* removed unused type.

* big refactor to make things simpler and to centralize all configure error/validation handling.

* added missing import.

* fixed failing tests.

* fixed tests.

* revert(extensions): remove static extensions config in favour of registering via AppPlugin APIs

* removed the compose that didn't work for some reason.

* added tests just to verify that validation and error handling is tied together in configuration function.

* adding some more values to the context.

* draft validation.

* added missing tests for getPanelMenu.

* added more tests.

* refactor(extensions): move logic for validating extension link config to function

* Fixed ts errors.

* Update packages/grafana-data/src/types/app.ts

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

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

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

* refactor(extensions): rename limiter -> pluginPlacementCount

* refactor(getpanelmenu): remove redundant continue statement

---------

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>
Co-authored-by: Marcus Andersson <marcus.andersson@grafana.com>

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

@@ -472,39 +472,6 @@
           "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", "placement", "path"],
-        "properties": {
-          "type": {
-            "type": "string",
-            "enum": ["link"]
-          },
-          "title": {
-            "type": "string",
-            "minLength": 3,
-            "maxLength": 22
-          },
-          "placement": {
-            "type": "string",
-            "pattern": "^(plugins|grafana)/[a-z-/0-9]*$"
-          },
-          "description": {
-            "type": "string",
-            "maxLength": 200
-          },
-          "path": {
-            "type": "string",
-            "pattern": "^/.*"
-          }
-        }
-      }
     }
   }
 }