RDP plugin rewrite

I´ve been contacted on https://matrix.to/#/!mnXPZoPpWIGqYeWkOf:matrix.org/$JBhpIt2b0_67CSqeigbexBIxczTqT4-D-Dev3fB0cIU?via=matrix.org&via=tchncs.de&via=matrix.dark-alexandr.net due to lacking clipboard support.

the plugin is in a quite sad state and I´ve rewritten it to conform to our sample client. (currently freerdp3 only, but can be extended to support 2.x versions as well with a few additions) (keep the RDP stuff on the same thread, use the client_common abstractions, ...)

see https://github.com/akallabeth/krdc/tree/freerdp3 (I´ve tried to commit to a fork of this repo here, but the hooks do not like my handle and I don´t use full names for private contributions)

• it should be working for what the plugin supports now, but is still lacking a lot of stuff (I don´t know how you handle UI dialogs, they should run on the UI thread and the callbacks from RDP are blocking, so someone more familiar with KDE/QT should most likely implement that)
• there are new authentication methods supported (PAA, AAD, smartcard, emulated smartcard if compiled) that need UI attention
• most channels are now implemented in client common abstractions, but clipboard and display resize channel are still to be done per client

if you have any questions, contact me on the freerdp matrix channel.