Import gclib relative to wwrando.py instead of current working directory

[Aelire]

Executing the randomizer from source currently only works when the working directory is the root of the repository, with gclib being loaded from a path relative to the working directory of the shell. This changes the gclib load path to be relative to the wwrando.py file so that it's possible to execute the randomizer from different directories. A similar method is already used in the assemble.py script here: https://github.com/LagoLunatic/wwrando/blob/ccb32a3cf1fcc398514f970039a775452217c1c5/asm/assemble.py#L14-L16

This might be linux-only (not sure how cwd works on other OS), and only shows up when running from source rather than release binaries (I tested that this change doesn't break a (linux) release binary though), so this is mostly for convenience when developing, but it would also be useful for the racetime.gg bot which can run multiple versions of the randomizer side-by-side

For example, on master when running from one directory up the tree it fails like this:

python wwrando/wwrando.py                                                                                                                                                                                                                                                                                                                                               
Traceback (most recent call last):
  File "<...>/wwrando/wwrando.py", line 294, in <module>
    run_with_ui(args)
  File "<...>/wwrando/wwrando.py", line 270, in run_with_ui
    from wwr_ui.randomizer_window import WWRandomizerWindow
  File "<...>/wwrando/wwr_ui/randomizer_window.py", line 5, in <module>
    from wwr_ui.uic.ui_randomizer_window import Ui_MainWindow
  File "<...>/wwrando/wwr_ui/uic/ui_randomizer_window.py", line 25, in <module>
    from wwr_ui.cosmetic_tab import CosmeticTab
  File "<...>/wwrando/wwr_ui/cosmetic_tab.py", line 20, in <module>
    import customizer
  File "<...>/wwrando/customizer.py", line 13, in <module>
    from gclib import fs_helpers as fs
ImportError: cannot import name 'fs_helpers' from 'gclib' (unknown location)
[1]    2494186 exit 1     python wwrando/wwrando.py