[Glitch] Add email subscriptions to profiles in web UI

Port 93dcca7f12 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/api/accounts.ts

@@ -75,3 +75,6 @@ export const apiDeleteProfileAvatar = () =>
 
 export const apiDeleteProfileHeader = () =>
   apiRequestDelete('v1/profile/header');
+
+export const apiSubscribeByEmail = (id: string, email: string) =>
+  apiRequestPost(`v1/accounts/${id}/email_subscriptions`, { email });