Expose Glint types

[simonihmig]

Update: after...

• fixing duplicated glint dependencies
• adding exports and typesVersions
• upgrading rollup-plugin-ts to v3

... this now seems to work perfectly, both with

• TS 4.6
• TS 4.7 and node16 module resolutions

---

This is not quite ready yet, as I need to figure out how the consuming app can import the glint module.

The thing is that this v2 addon uses exports, but

• only the upcoming TS 4.7 will support that
• and that also hasn't really worked

Something like this worked in the IDE, but Glint was still not seeing the types added to the registry:

"exports": {
    "./glint": {
      "types": "./dist/glint.d.ts"
    },
    "./*": {
      "types": "./dist/*",
      "default": "./dist/*"
    },
    "./addon-main.js": "./addon-main.js"
  }