Add Oscar wrappers for GAP's CodePcGroup and PcGroupCode

[varuntrehan7]

I've added functions to wrap CodePcGroup and PcGroupCode and the doctoring,testsets with respect to it. let me know for any corrections, also unsure where I need to import so for the time being they're inside my testset.

[varuntrehan7]

additional comment, whenever I try to push a new branch it also shows the commit from 2 months ago that I did on fixed-points, I am not sure what I should do there.

[fingolfin]

Difficult to say with so little information what went wrong (I'd say come by tomorrow afternoon for the OSCAR coding sprint and we can quickly get it fixed, but I think you are still out of the country, right?)

In the meantime, you should first make sure your local master (in your git clone of Oscar.jl) matches the master on oscar-system/Oscar.jl. (Take a look at git log master, it should list comments from today at the top). Once this is done, you can then move on to correcting this branch here (I can write more but let's first establish that your master is up-to-date)

[varuntrehan7]

I have raised #5456 to accomodate the latest master commits. Hence, closing this PR.