Add colors to d2r-loot-filters & use command_exists instead of command -v

[nnyyxxxx]

Type of Change

• [x] 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

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