Move API Reference (#23777)

* merge mattermost-api-reference unchanged

* api: update repostiory paths

* api: drop GitPod for api (for now)

* api: improved node_modules target

* api: relocate GitHub actions to root

* Update .github/workflows/api.yml

Co-authored-by: Antonis Stamatiou <stamatiou.antonis@gmail.com>

* fix cache-dependency-path

* adopt node-version-file

* pin versions for uses

* tidy steps/runs

* api/.gitpod.yml: tidy

* api: rm now unused .gitlab-ci.yml

---------

Co-authored-by: Antonis Stamatiou <stamatiou.antonis@gmail.com>

api/v4/source/bleve.yaml

@@ -0,0 +1,28 @@
+  /api/v4/bleve/purge_indexes:
+    post:
+      tags:
+        - bleve
+      summary: Purge all Bleve indexes
+      description: >
+        Deletes all Bleve indexes and their contents. After calling this
+        endpoint, it is
+
+        necessary to schedule a new Bleve indexing job to repopulate the indexes.
+
+        __Minimum server version__: 5.24
+
+        ##### Permissions
+
+        Must have `sysconsole_write_experimental` permission.
+      operationId: PurgeBleveIndexes
+      responses:
+        "200":
+          description: Indexes purged successfully.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/StatusOK"
+        "500":
+          $ref: "#/components/responses/InternalServerError"
+        "501":
+          $ref: "#/components/responses/NotImplemented"