apply: improve error messages when reading patch

apply: improve error messages when reading patch

Commit f1c0e3946e (apply: reject patches larger than ~1 GiB, 2022-10-25)
added a limit on the size of patch that apply will process to avoid
integer overflows. The implementation re-used the existing error message
for when we are unable to read the patch. This is unfortunate because (a) it
does not signal to the user that the patch is being rejected because it
is too large and (b) it uses error_errno() without setting errno.

This patch adds a specific error message for the case when a patch is
too large. It also updates the existing message to make it clearer that
it is the patch that cannot be read rather than any other file and marks
both messages for translation. The "git apply" prefix is also dropped to
match most of the rest of the error messages in apply.c (there are still
a few error messages that prefixed with "git apply" and are not marked
for translation after this patch). The test added in f1c0e3946e is
updated accordingly.

Reported-by: Premek Vysoky <Premek.Vysoky@microsoft.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>