Add colors to d2r-loot-filters

[nnyyxxxx]

Type of Change

• Refactoring

Description

quotes vars to prevent globbing, adds colors, uses command_exists function defined in common-script

Testing

needs testing, though it should work fine. can't test because i don't own the game, but the first 18 lines work:

Checklist

• My code adheres to the coding and style guidelines of the project.
• I have performed a self-review of my own code.
• My changes generate no errors/warnings/merge conflicts.