Add looking to play text channel in discord

Benefits:
1) We can create pinned messages, where we schedule events, this easies organising 10v10 matches or matches, where map makers can collectively test each others maps for example.
2) Removes spam from intruder-general.
3) New discorders know immediately, where to go, if they are looking for players.
4) If you are not in ltp category and want to suddenly play, the looking to play messages are not lost in other general related chitchat
5) Lower threshold to ask people to play as you are not interrupting people and their chitchat in #intruder-general