Handle modifications in extensionless zip files (bug#61326)

Handle modifications in extensionless zip files (bug#61326)

* lisp/arc-mode.el (archive-*-write-file-member)
(archive-*-expunge): Refactor to correctly modify
extensionless zip archives.
(archive-expunge): Move implementation to a separate helper
function to facilitate testing.
(archive--act-files): New helper function to wrap around
`call-process' calls.
(archive--need-rename-p): New helper function to check whether
a temporary rename is necessary.
(archive--ensure-extension) (archive--maybe-rename): New helper
functions to rename archive if the caller deems it necessary.
(archive--with-ensure-extension): New helper function to handle
writing an archive while ensuring extensionless archives work
correctly by temporarily renaming them.

* test/lisp/arc-mode-tests.el (arc-mode-test-zip-ensure-ext):
New regression test for bug#61326.