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](https://github.com/Homebrew/homebrew-core/commit/6e536ff007ef0bea5a3591af5678eb3152908cc9)
to make installation easier (for os x users at least)

CHANGELOG.md

@@ -0,0 +1,16 @@
+## main
+
+### ✨ Features and improvements
+- Add GitHub workflows for releasing new versions
+- Update desktop build to pull from this repo (#922)
+- _...Add new stuff here..._
+
+### 🐞 Bug fixes
+- _...Add new stuff here..._
+
+## 2.0.0
+- Update MapLibre to version 4 (#872)
+
+## 1.7.0
+- See release notes at https://maputnik.github.io/blog/2020/04/23/release-v1.7.0
+