Add "setuid and setgid" technique (T1166)

[shreyamalviya]

T1166

setuid or setgid bits are set on Linux so that the application will run with the privileges of the owning user or group respectively, instead of the user or the group of the user launching it.
Adversaries can use this to either do a shell escape or exploit a vulnerability in an application with the setuid or setgid bits to get code running in a different user’s context.

Adding it as PBA:
- LINUX: try modifying file permissions using chown and chmod; see this and this
- WINDOWS: not applicable

Mapping the technique to the ATT&CK matrix