Start the merging-rebase to v2.22.0-rc2

In preparation for Git for Windows v2.22.0-rc2, we also use this
opportunity to "fake-merge" Git for Windows' current `master` (i.e. this
merging-rebase starts not with a regular merge, but with an octopus
merge that makes both v2.22.0-rc1.windows.1 *and* `master` reachable).

While at it, we also reorder more patches, in particular moving more
things into the `ready-for-upstream` branch thicket.

This commit starts the rebase of 4611617 to 8cda320

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho