feat: allow enable/disable option for icons

[tdback]

Checklist

• Used only camelCase variable names.
• If functionality is added or modified, also made respective changes to the
  README.md (the .txt file is auto-generated and does not need to be modified).

This feature allows someone to enable or disable the use of icons in their configuration without having to manually set the value of each hint to "". This is helpful when someone is using an un-patched font, or one that doesn't contain icons.

[chrisgrieser]

Thanks for the PR, but why not just set the icons to "" if you want to disable them?

[tdback]

I initially found myself looking for an option to enable/disable, as I feel it's quite common across other plugins. Given there's only a few options I would have to change to remove icons it's not too much of a hassle if it doesn't get merged. Just thought I'd add it in!

[chrisgrieser]

I see. I think for the sake of keeping the plugin as minimal as possible, I think "" should suffice to disable them.

Other plugins may have a separate toggle, but that's probably cause they simply have a lot of icons.