Add the two config constants from C git that can switch on signing
of annotated tags. Add them to the GpgConfig, and implement actually
signing a tag in TagCommand.
The interactions between command line options for "git tag" and config
options is a bit murky in C git. There are two config settings for it:
* tag.gpgSign is the main option, if set to true, it kicks in if
neither -s nor -u are given on the command line.
* tag.forceSignAnnotated signs only tags created via "git tag -m",
but only if command-line option "-a" is not present. It applies
even if tag.gpgSign is set explicitly to false.
Giving -s or -u on the command line also forces an annotated tag
since lightweight tags cannot be signed.
Bug: 386908
Change-Id: Ic8a1a44b5f12f47d5cdf3aae2456c1f6ca9ef057
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
41b9159795