Draft: Add support for FullChain additional output format

[svvac]

Pull Request Motivation

Allow exporting a complete certificate chain, including the root. See #6876.

Kind

feature

Release Note

Add support for FullChain additional output format

Bikeshedding

• Output format name : FullChain
• Output secret key : tls-full-chain.pem

Alternatives

An alternative could be a flag on the Certificate for requesting a full chain in tls.crt. In the case of long chains, this could save data usage on the Secret, if you consider the user is unlikely to use both chains separately.

Further work

I'd like to put this out there to get the ball rolling before continuing working on the tests.

[cert-manager-prow]

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[cert-manager-prow]

Hi @svvac. Thanks for your PR.

I'm waiting for a cert-manager member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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