pidgin/pidgin

Add a description to PurpleCredentialProvider and show it in the preferences selector

Testing Done:
Compiled and ran locally.

Reviewed at https://reviews.imfreedom.org/r/539/
syntax: glob
.*.swp
.DS_Store
.flatpak-builder
*.pyc
*~
\#*\#
subprojects/*/
syntax: regexp
^build(.+)?\/
win32-install-dir(\.release)?
po\/pidgin\.pot$