Kernel prepatch 6.19-rc7

So normally this would be the last rc of the release, but as I've mentioned every rc (because I really want people to be aware and be able to plan for things) this release we'll have an rc8 due to the holiday season.

And while some of the early rc's were smaller than usual and it didn't seem necessary, right now I'm quite happy I made that call. Not because there's anything particularly scary here - the release seems to be going fairly smoothly - but because this rc7 really is larger than things normally are and should be at this point.

Along with the usual fixes, this -rc also includes a new document describing the process to replace the kernel project leadership should that become necessary in the absence of an arranged transition. The plan largely follows what was decided at the Maintainers Summit in December.