pidgin/pidgin

Convert credentials page to use HdyPreferencesGroup and a list box.

2021-05-12, Elliott Sales de Andrade
68c7ef6c5320
Convert credentials page to use HdyPreferencesGroup and a list box.

* Convert credentials page to use `HdyPreferencesGroup` and a list box.
* Add widget for displaying a credential provider in a list box.
* Convert `PidginCredentialsPage` into `HdyPreferencesPage`.

Testing Done:
Opened Preferences, switch to Credentials page, and see/toggle selected provider.

Reviewed at https://reviews.imfreedom.org/r/644/
#tab-label-typing {
color: #4e9a06;
}
#tab-label-typed {
color: #c4a000;
}
#tab-label-attention {
color: #006aff;
}
#tab-label-unreadchat {
color: #cc0000;
}
#tab-label-event {
color: #888a85;
}