New settings regarding names

[NicEastvillage]

While making #72, two ideas for new match config settings came to mind:

• rlbot.allow_empty_names (default false): If false, empty names are replaced by "Unnamed".
• rlbot.allow_duplicate_names (default false): If false, the names are appended a number, e.g. (2).

They are purely QoL features with no demand, but also easy to make.

[VirxEC]

Both of these options may or may not cause weird bugs in code (either core or bots) that expect all names to be unique

Could still be options though I'm not against it

[VirxEC]

Due to problem brought up in #143 with duplicate names confusing Rocket League, perhaps these things should not be allowed?

I guess it technically "works" still...