Highlight the suffix .L and .R on bones

Might be a bit of a stretch, but after seeing someone struggle for a bit with Symmetrize, I had the thought of adding a visual feedback (ex.: colored text, box highlight, underline) when a special naming convention suffix is present in the bone name. Example:

Alternative (underline):

As well as giving a clearer indicator for new users about these suffixes, it would be convenient to see them at a glance slightly quicker. Other thoughts:

• Should work with all valid separators mentioned in the manual (underscore, dot, dash, space)
• Should also be used in other supported suffixes (.Bk/.Fr, .Top/.Bot...maybe .001?) - docs.blender.org/manual/en/latest/animation/armatures/bones/editing/naming.html
• Toggleable, of course