feat(useLocale): handle generic messages (#3100)

Co-authored-by: hywax <me@hywax.space>
Co-authored-by: Benjamin Canac <canacb1@gmail.com>

src/runtime/types/locale.ts

@@ -50,9 +50,9 @@ export type Messages = {
 
 export type Direction = 'ltr' | 'rtl'
 
-export type Locale = {
+export type Locale<M> = {
   name: string
   code: string
   dir: Direction
-  messages: Messages
+  messages: M
 }