GGUF Q6K WA for GPU (openvinotoolkit#2135)

Base on openvinotoolkit#2120

Mainly features:

1. Q6_K is not supported by some platforms GPU because of weight
compression w/ group size 16, so we use F16 as a workaround
2. Format file gguf.cpp

Tickets:
CVS-166026
CVS-166027
CVS-166739

Author: TianmengChen