Consolidate use of monarch lexer

[somebee]

We currently have three(!) nearly identical copies of the imba monarch lexer in the repo. Right now it is mostly used in the typescript-imba-plugin, but we also have a need for it in vscode-imba and various other tooling related projects. To clean this up we need to ...

• [ ] Make typescript-imba-plugin depend on the imba-monarch code and remove typescript-imba-plugin/src/lexer dir
• [ ] Make imba depend on imba-monarch code and remove the imba/src/program files
• [ ] Publish imba-monarch as a separate package
• [ ] Use imba-monarch in vscode-imba to do semantic coloring outside of the typescript-imba-plugin