Emacs 30 - first snapshot to alpha

[Corwin Brust]

Windows users: first snapshot build of Emacs 30 (from the master
branch) is on (or will soon be on your favorite mirror of) alpha,
e.g.:

https://alpha.gnu.org/gnu/emacs/pretest/windows/emacs-30/?C=M;O=D

NOTE: You may notice a missing README file. I will update the (new)
emacs-30 folder with a readme as soon as I can.  Meanwhile, please
refer to the README in the "sibling" emacs-29 folder, and don't
hesitate to send me any questions.

TIA for letting me know of issues, should you get a chance to test these out!

PS, there's a new snapshot in the "emacs-29" folder as of yesterday,
too.  This corrects an issue where the full zip didn't contain the
deps DLLs and is based on a slightly more recent commit to the release
branch.  If you are using emacs-64a2b0d36fe{.zip,-installer.zip}, you
can add the missing DLLs by unpacking emacs-29-deps-20230310.zip (also
in the emacs-29 folder) into the bin folder of your installed Emacs.

Corwin