Update desktop build to pull from this repo (#922)

Previously the desktop build lived in a separate repo and had to
download a released version of the maputnik editor source code. Now that
both live in the same repo, the desktop version can simply run the
maputnik build command and use those generated files.

This commit also removes the ci-desktop workflow, which is not needed.
The regular ci workflow already built the desktop version (this commit
also fixes that build).

Fixes #919

If this works for you all, it would be lovely to create a new tag or
release on GitHub for two reasons:
1. So the latest binaries are easier to locate, and
2. So I can update my [submission to
homebrew](6e536ff007)
to make installation easier (for os x users at least)

README.md

@@ -94,6 +94,16 @@ You can also see the tests as they run or select which suites to run by executin
 npm run cy:open
 ```
 
+## Release process
+
+1. Review [`CHANGELOG.md`](/CHANGELOG.md)
+   - Double-check that all changes included in the release are appropriately documented.
+   - To-be-released changes should be under the "main" header.
+   - Commit any final changes to the changelog.
+2. Run [Create bump version PR](https://github.com/maplibre/maputnik/actions/workflows/create-bump-version-pr.yml) by manual workflow dispatch and set the version number in the input. This will create a PR that changes the changelog and `package.json` file to review and merge.
+3. Once merged, an automatic process will kick in and creates a GitHub release and uploads release assets.
+
+
 ## Sponsors
 
 Thanks to the supporters of the **[Kickstarter campaign](https://www.kickstarter.com/projects/174808720/maputnik-visual-map-editor-for-mapbox-gl)**. This project would not be possible without these commercial and individual sponsors.