Add rpmkeys --export

[ffesti]

Just writes the keys out to stdout in an ASCII armored format.

Resolves: #3366

May be an option to write the keys into different files with the fingerprints as a filename might also be handy.

[pmatilai]

May be an option to write the keys into different files with the fingerprints as a filename might also be handy.

Nah, let's not invent options for theoretical use-cases. This is unix, and we're just handing people the tools to do whatever they please with this data:

for key in $(rpmkeys --list|cut -f1 -d' '); do rpmkeys --export ${key} > ${key}.asc; done