Fixed pkg-config files generation

[ilya-lavrenov]

1. Currently, pkg-config files are generated with hardcoded paths to libs and includes.

I.e. if I build level-zero on one machine with non-default paths and try to use such package on another, paths will be broken.
It's valid for conda-forge, which builds packages within internal structure and then paths look like:

/home/conda/feedstock_root/build_artifacts/intel-level-zero_1732035758241/work/install/include

which cannot be used by users of level-zero-devel package.

The solution is to use relative paths.

2. Renamed utils to level_zero_utils as utils is quite common name and clashes with other projects when level-zero is used as sub-project in a bigger project.

3. Use PUBLIC / PRIVATE when link libraries to hide private libraries like utils

[ilya-lavrenov]

@lisanna-dettwyler please, have a look