MainWindow: add icons for map source buttons

[danirabbit]

Do something a bit more visually interesting with the map options submenu:

• Create icons for map sources
• I changed the names of the maps because I don't think "Mapnik" means anything to most people and I think "Transit" is probably better American English. I'm not terribly attached to "Explore" I just couldn't think of a better name and this is what Apple Maps calls it. Google Maps just calls it "Default"
• Add color scheme options as a section instead of a submenu

[ryonakano]

Explore always looks as if selected (just focused actually) even if you select Transit and reopen the popover 🤔

[danirabbit]

Explore always looks as if selected (just focused actually) even if you select Transit and reopen the popover

@ryonakano Yeah this is more of a stylesheet bug because it's using :focus instead of :focus-visible for its keyboard focus styles. I'd prefer to address it there

[danirabbit]

Proposed elementary/stylesheet#1330

[ryonakano]

Proposed elementary/stylesheet#1330

Thank you for your quick fix, I confirmed the issue resolved with latest main branch of stylesheet:

diff --git a/io.elementary.maps.yml b/io.elementary.maps.yml
index 914e5af..5ea5bf4 100644
--- a/io.elementary.maps.yml
+++ b/io.elementary.maps.yml
@@ -12,6 +12,37 @@ finish-args:
 build-options:
   libdir: /app/lib
 modules:
+  - name: sassc
+    buildsystem: autotools
+    sources:
+      - type: archive
+        url: https://github.com/sass/sassc/archive/3.6.2.tar.gz
+        sha256: 608dc9002b45a91d11ed59e352469ecc05e4f58fc1259fc9a9f5b8f0f8348a03
+      - type: script
+        dest-filename: autogen.sh
+        commands:
+          - autoreconf -si
+    modules:
+      - name: libsass
+        buildsystem: autotools
+        sources:
+          - type: archive
+            url: https://github.com/sass/libsass/archive/3.6.5.tar.gz
+            sha256: 89d8f2c46ae2b1b826b58ce7dde966a176bac41975b82e84ad46b01a55080582
+          - type: script
+            dest-filename: autogen.sh
+            commands:
+              - autoreconf -si
+
+  - name: stylesheet
+    buildsystem: meson
+    cleanup:
+      - /share/metainfo
+    sources:
+      - type: git
+        url: https://github.com/elementary/stylesheet.git
+        commit: 3d7e2b74ad8bddb19128bc2afaeaa7e343f8046a
+
   - name: geocode-glib-2.0
     buildsystem: meson
     config-opts:

[ryonakano]

I really love this design, thank you very much!