[snapcraft.yml] rsync shared files from $SNAP/share/ to $SNAP/usr/share/

It appears that CHIRP is being installed with a `prefix=/` instead of `prefix=/usr`
Rather than move a bunch of files around and change the entire snap, I'm rsync'ing $SNAP/share to $SNAP/usr/share

Open question at: https://forum.snapcraft.io/t/python-install-prefix/31248
What I believe is the python plugin handling the CHIRP install: https://github.com/snapcore/snapcraft/blob/main/snapcraft_legacy/plugins/v2/python.py
In response to: #1

snap/snapcraft.yaml

@@ -77,6 +77,10 @@ parts:
     override-build: |
       snapcraftctl build
       cp ${SNAPCRAFT_PART_SRC}/share/chirp.svg ${SNAPCRAFT_PART_INSTALL}/share/chirp-snap.svg
+      rsync -av ${SNAPCRAFT_PART_INSTALL}/share/ ${SNAPCRAFT_PART_INSTALL}/usr/share/
+      rm ${SNAPCRAFT_PART_INSTALL}/usr/share/pixmaps/chirp.png
+    build-packages:
+      - rsync
     stage-packages:
       - python-gtk2
       - python-serial