Add PS2 support in create_config

[AngheloAlf]

Adds support for PS2 ELFs in create_config by using the "fake rom" approach.
This avoid issues in the long run generating elf within an elf in the build system, but adds objcopy as a dependency of create_config for PS2. Since we can't know what objcopy flavour the user may want to use then create_config will try to figure out which one the user has from a list. The user can also provide their own objcopy by passing a flag.

The generated yaml is generated from the elf and it includes info like each section from the game and automatically fill section_order and similar variables, gp value if available and a ld_gp_expression setting when possible, inferred compiler and tweaked default settings for ps2.
The compiler inferring machinery is pretty weak. Currently it assumes EEGCC unless there's a .mwcats section present in the ELF. I think this should be good enough as an starting point, and we can improve this in the future.

Since splat doesn't have built-in support for vutext, vudata, etc, those kind of sections will be listed as incbins instead.

I also wrote some docs in a separate Quickstart page. Hopefully everything is clear enough.

I'm not sure how to bump the splat version. Should I do +0.1.0 or +0.0.1?