pidgin/pidgin

Clean up PidginCredentialManager

2021-07-18, Gary Kramlich
671f2442e50e
Clean up PidginCredentialManager

* Remove the unnecessary _provider from a bunch of symbols
* Use g_task_return_new_error
* Some other minor cleanups

Testing Done:
Compiled and ran the unit tests.

Reviewed at https://reviews.imfreedom.org/r/804/
libpurple/data/purple-url-handler.desktop.in
libpurple/protocols/null/nullprpl.c
pidgin/data/im.pidgin.Pidgin.desktop.in
sub/libpurple/data/purple-url-handler.desktop.in
sub/libpurple/protocols/null/nullprpl.c
sub/pidgin/data/im.pidgin.Pidgin.desktop.in