Adopts Qt 5.14 which has several ramifications, biggest being Qt now
builds both arm32 and arm64 together. This merges both images back into
teh one which can produce all of the binaries.
It makes the image considerably bigger but doesn't make us have to use
two of them, which is helpful.

This also changes most of our tooling to produce both architectures per
run, it seems to work fine but more testing is needed.

For cmake we'll be just producing two separate prefixes. It's not ideal
but it works for now.