feat(mac-crafter): retry code-signing attempts

feat(mac-crafter): retry code-signing attempts

This step sometimes fails with an error such as: "A timestamp was
expected but was not found.".  Any code-signing errors will result in
the notarisation step to fail.

Apparently this might be due to intermittent network issues.  Let's just
retry codesigning a couple of times in the case it fails ...

See also: https://developer.apple.com/documentation/security/resolving-common-notarization-issues#Include-a-secure-timestamp

Signed-off-by: Jyrki Gadinger <nilsding@nilsding.org>