Improve ghidra2cpg program loading

[dotCirill]

Add ability to load program from existing Ghidra project (GPR)

[dotCirill]

#2534

The usage is something like this:

# Ghidra project "ghidra_project" in folder "/home/user/Desktop/"
# Program at the root of project is "TheBinary"
./ghidra2cpg  "gpr::/home/user/Desktop/ghidra_project::/TheBinary" -o from_gpr.cpg 
./ghidra2cpg  "/bin/ls" -o from_binary_auto_analyze.cpg 

It requires to handled project name and program name within project.

It will probably be better to create extra command-line options for ghidra2cpg.

[dotCirill]

Error handling can be better. It cannot open ghidra project when it's opened in ghidra (project in locked), but error message is meanless (could not open the project).

Also ghidra version must be the same (10.3).

[itsacoderepo]

@dotCirill Thanks for the PR! I haven't forgotten it, just have been busy. I'll probably have to rewrite it here and there though.