Adapt for Magit's move to Transient

[bmag]

Magit now uses Transient instead of magit-popup, and we must adapt. Also had to replace the recently removed magit-diff-buffer-file-popup with magit-diff-buffer-file (similar but doesn't offer a popup before displaying the diff).

Note some upstream packages haven't adapted to this change, but when they do we might need similar fixes:

• magithub
• magit-gitflow
• magit-svn

Related: #11978

[duianto]

Could magit-diff be the new equivalent command?

This is what the SPC g f d (magit-diff-buffer-file-popup) popup looked like before:

This is what SPC g f d (magit-diff-buffer-file) looks like now:

This is what M-x magit-diff looks like now:

And pressing d (for Dwim), shows a prompt: Diff for range (magit-transient-PR):
Pressing RET shows the same buffer as SPC g f d (second screenshot) but with a shorter buffer name magit-diff: .emacs.d.

[duianto]

Or if magit-diff isn't correct, then maybe magit-file-dispatch (C-c M-g) works better.

The popup looks different:

but pressing d shows the same buffer as in the second screenshot above, with the long buffer-name (that includes the current file name).

Pressing D from that popup shows the same popup as in the third screenshot above.

[syl20bnr]

Thank you ! 💯

[domenzain]

Related: syl20bnr/evil-escape#90
Although magit is useable, with the latest develop, evil-escape fails to escape from these transient windows.