[tstool.py update] Remote Desktop Shadowing feature support

[fulc2um]

This pull request brings necessary enumerations to tsts.py and tstool.py to utilize the Shadowing features of Remote Desktop services:

• https://swarm.ptsecurity.com/remote-desktop-services-shadowing/
• https://blog.bitsadmin.com/spying-on-users-using-rdp-shadowing

Implemented:

• SessEnvPublicRpc interface
• RpcShadow2 method call

Complete workflow:
0. Make sure you have the permissions and network visibility

1. Enable shadowing using any method (gpo/reg.exe or nxc -M shadowrdp)
2. Enumerate active sessions (qwinsta or nxc --qwinsta)
3. tstool.py '<domain>/<username>':'<password>'@<host> shadow -session <target_session_id> // optional arguments: [-control|-prompt|-file]; format of the file: .msrcIncident
4. xfreerdp invite.msrcIncident

Demo:

lin_ver_sp_lq.mov

[snovvcrash]

Another private feature is in public now... Great job @fulc2um!

[Dfte]

Holy shit it's so fucking cool someone actually implemented it into Impacket!!!!!

[anadrianmanrique]

@fulc2um thanks for the PR. This seems to be an interesting functionality. I requested some minors changes to have this merged. Aside from that, I used xfreedrp to test this. I don't know yet why, but I've got errors, in some iterations. It doesn't seem to be a consistent behavior. I don't know whether there's a problem in xfreerdp per se or in the xml file. So, every time I get an error, I re execute tstool.py to generate again the xml invite file, and then it works ok...

[anadrianmanrique]

Thanks, now PR is ready to be merged.