feat(bootstrap): track subiquity's main branch (#811)

This sets up the main development branch in this repo to track
subiquity's `main` branch. I've included @ogayot's change #769 for the
type generator and used it to update the Dart classes. I also removed
some remaining parts of the decommissioned WSL setup (see internal spec
WS030), since the the corresponding types have been removed from
subiquity.

For additional 24.04.x bug fixes we will use the new `ubuntu/24.04`,
which still tracks subiquity's `ubuntu/noble` branch.

I'm also removing the remaining snapcraft files for
ubuntu-desktop-bootstrap here.
We're migrating to the new setup (internal specs UD064 and UD068) with
the snapcraft files now located on dedicated branches
(`snap/ubuntu-destkop-bootstrap/main` in this case).
I'll follow up with a proper documentation update next week.

.github/workflows/ci.yml

@@ -28,16 +28,6 @@ jobs:
       - uses: bluefireteam/melos-action@v3
       - run: melos analyze --fatal-infos
 
-  consistency-check:
-    runs-on: ubuntu-22.04
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          submodules: recursive
-      - name: Check actual subiquity submodule sha matches expected
-        run: |
-          ci/subiquity_integration
-
   bootstrap:
     runs-on: ubuntu-22.04
     strategy:

.gitmodules

@@ -1,4 +1,4 @@
 [submodule "subiquity"]
 	path = packages/subiquity_client/subiquity
 	url = https://github.com/canonical/subiquity.git
-	branch = ubuntu/noble
+	branch = main