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>

pkg/plugins/plugindef/plugindef.cue

@@ -3,7 +3,7 @@ package plugindef
 import (
 	"regexp"
 	"strings"
-	
+
 	"github.com/grafana/thema"
 )
 
@@ -122,23 +122,6 @@ seqs: [
 					...
 				}
 
-				#ExtensionsLink: {
-					// Target where the link will be rendered
-					placement: =~"^(plugins|grafana)\/[a-z-/0-9]*$"
-					// Type of extension
-					type: "link"
-					// Title that will be displayed for the rendered link
-					title: string & strings.MinRunes(3) & strings.MaxRunes(22)
-					// Description for the rendered link
-					description: string & strings.MaxRunes(200)
-					// Path relative to the extending plugin e.g. /incidents/declare
-					path: =~"^\/.*"
-					...
-				}
-
-				// Extensions made by the current plugin.
-				extensions?: [...#ExtensionsLink]
-
 				// For data source plugins, if the plugin supports logs.
 				logs?: bool