Updates link color to use the design token and adds missing
text color tokens for mention link.

feat(GlLink): Add and update tokens

See merge request !4579



Merged-by: Mark Florian <mflorian@gitlab.com>
Approved-by: Ian Gloude <igloude@gitlab.com>
Approved-by: Mark Florian <mflorian@gitlab.com>
Approved-by: Dan MH <dmizzi-harris@gitlab.com>
Reviewed-by: Ian Gloude <igloude@gitlab.com>
Co-authored-by: Sascha Eggenberger <seggenberger@gitlab.com>

# [91.8.0](v91.7.0...v91.8.0) (2024-09-04)

### Features

* **GlLink:** Add and update tokens ([df90a002](df90a002))