Refactor texture overrides and add new features (#9600)

Refactor texture overrides and add new features (#9600)

* Refactor texture overrides, and add new features:

- Texture overrides can support multiple targets in one line
- Texture override files can have comment lines
- Item images/wield images can be overridden

* Formatting changes

* Address soime feedback

- Pass vectors by const reference
- Log syntax errors as warnings
- Remove 'C' prefix from TextureOverrideSource

* Simplify override target checks with an inline helper function

* make linter happy

* Apply feedback suggestions

Co-Authored-By: rubenwardy <rw@rubenwardy.com>
* Remove remaining != 0 checks

* Update copyright notice

Co-authored-by: sfan5 <sfan5@live.de>
Co-authored-by: rubenwardy <rw@rubenwardy.com>