split up PowerLevelEditor into two components

one while editing (PowerLevelEditor) and one
while not editing (PowerLevelSection).

Also save when pressing the button, not when changing the
power dropdown.

Also show the spinner next to the dropdown when saving,
not at the bottom of the component.

src/i18n/strings/en_EN.json

@@ -118,7 +118,7 @@
     "Restricted": "Restricted",
     "Moderator": "Moderator",
     "Admin": "Admin",
-    "Custom %(level)s": "Custom %(level)s",
+    "Custom (%(level)s)": "Custom (%(level)s)",
     "Start a chat": "Start a chat",
     "Who would you like to communicate with?": "Who would you like to communicate with?",
     "Email, name or Matrix ID": "Email, name or Matrix ID",
@@ -1080,8 +1080,8 @@
     "Remove this user from community?": "Remove this user from community?",
     "Failed to withdraw invitation": "Failed to withdraw invitation",
     "Failed to remove user from community": "Failed to remove user from community",
-    "Failed to deactivate user": "Failed to deactivate user",
     "<strong>%(role)s</strong> in %(roomName)s": "<strong>%(role)s</strong> in %(roomName)s",
+    "Failed to deactivate user": "Failed to deactivate user",
     "This client does not support end-to-end encryption.": "This client does not support end-to-end encryption.",
     "Messages in this room are not end-to-end encrypted.": "Messages in this room are not end-to-end encrypted.",
     "Messages in this room are end-to-end encrypted.": "Messages in this room are end-to-end encrypted.",