FEAT: Allow users to view pending follow requests they sent

This commit implements the `following/requests/sent` interface firstly
implemented on Firefish, and provides a UI interface to view the pending
follow requests users sent.

packages/misskey-js/etc/misskey-js.api.md

@@ -1502,6 +1502,8 @@ declare namespace entities {
         FollowingRequestsCancelResponse,
         FollowingRequestsListRequest,
         FollowingRequestsListResponse,
+        FollowingRequestsSentRequest,
+        FollowingRequestsSentResponse,
         FollowingRequestsRejectRequest,
         GalleryFeaturedRequest,
         GalleryFeaturedResponse,
@@ -2023,6 +2025,12 @@ type FollowingRequestsListResponse = operations['following___requests___list']['
 // @public (undocumented)
 type FollowingRequestsRejectRequest = operations['following___requests___reject']['requestBody']['content']['application/json'];
 
+// @public (undocumented)
+type FollowingRequestsSentRequest = operations['following___requests___sent']['requestBody']['content']['application/json'];
+
+// @public (undocumented)
+type FollowingRequestsSentResponse = operations['following___requests___sent']['responses']['200']['content']['application/json'];
+
 // @public (undocumented)
 type FollowingUpdateAllRequest = operations['following___update-all']['requestBody']['content']['application/json'];