* ci: bake appveyor images automatically, run sync on depshash change

* build: fixup appveyor image for release

* build: make sure symstore is in the PATH when baking an image

* build: update to use fixed baked image

* cleanup sdk install

* chore: fix test process.arch (doesn't work on arm)

Co-authored-by: John Kleinschmidt <jkleinsc@electronjs.org>