Add support for NerdFont glyphs

**As a** user of NerdFont glyphs and unicode escape sequences,
**I want** to see the glyphs for NerdFont codepoints in the hover tooltip
**So that** I can more easily read Oh-My-Posh templates (for example, see [Agnoster](https://github.com/JanDeDobbeleer/oh-my-posh/blob/main/themes/agnoster.omp.json) in the oh-my-posh repo)