feat: push signing keys to remote

[sweatybridge]

What kind of change does this PR introduce?

feature

What is the new behavior?

Support updating signing keys with config push.

Additional context

TODO:

• handle multiple standby keys

[coveralls]

Pull Request Test Coverage Report for Build 16681317174

Details

• 11 of 13 (84.62%) changed or added relevant lines in 1 file are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.03%) to 55.244%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/gen/signingkeys/signingkeys.go	11	13	84.62%

Files with Coverage Reduction	New Missed Lines	%
internal/gen/keys/keys.go	5	12.9%

Totals
Change from base Build 16677900504:	-0.03%
Covered Lines:	6184
Relevant Lines:	11194

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💛 - Coveralls

[hf]

Pushing a signing key is OK but it should come with a huge warning that the security of the key relies on the security of the device and person making the push.