nogaim: Match case in imc_away_state_find()
Match the provided away-state case when searching for an alias, better
matching expectations.
For example, bitlbee-discord provides this:
m = g_list_prepend(m, "invisible");
m = g_list_prepend(m, "dnd");
m = g_list_prepend(m, "online");
m = g_list_prepend(m, "idle");
/away DND - some reason
...gives "dnd", which matches what was given to Bitlbee.
/away Busy - some reason
...gives "DND", which does NOT match what was given to Bitlbee. The
capitalization is derived from using Bitlbee's built-in alias list.
Technically this is a breaking behavior change to Bitlbee's plugin
API, even if this behavior may make more sense.
See https://github.com/sm00th/bitlbee-discord/pull/230#issuecomment-1005468508
