[native] [web] Use tinycolor when comparing colors represented as strings

Summary: Recently have run into some bugs with checking color equality between two hex strings (using the basic === operator). Changed this equality (or inequality) check to use tinycolor.equals() instead throughout the codebase.

Test Plan: Tested LoadingIndicator and ThreadSettings on web and ensured that they looked as expected after the change.

Reviewers: atul

Reviewed By: atul

Subscribers: ashoat, palys-swm, Adrian

Differential Revision: https://phab.comm.dev/D4243