Migrate mockery to packages feature (#29013)

server/channels/store/.mockery.yaml

@@ -0,0 +1,10 @@
+with-expecter: false
+packages:
+  github.com/mattermost/mattermost/server/v8/channels/store:
+    config:
+      include-regex: ".*Store"
+      dir: "channels/store/storetest/mocks"
+      filename: "{{.InterfaceName}}.go"
+      mockname: "{{.InterfaceName}}"
+      outpkg: mocks
+      note: "Regenerate this file using `make store-mocks`."