Keepass support via go library

[bakito]

Is your feature request related to a problem? Please describe.

When using secrets from keepass, it would be nice in it would work without a dependency of keepassxc-cli.
Especially when flatpak is used and a wrapper script has to be used for the cli.

Describe the solution you'd like

Using this library github.com/tobischo/gokeepasslib could make chezmoi independent of the cli.

Describe alternatives you've considered

Using a wrapper script for the cli with flatpak.

Additional context

[halostatue]

We would need to verify that it could work with Yubikeys since a number of chezmoi users use Keepass with yubikeys. I see no mention of yubikeys in the codebase.

[bakito]

True, this seems not to be supported.

[twpayne]

I still think this is worth adding, even if it doesn't support the full range of KeepassXC functionality at the moment.

[bakito]

@twpayne I already id some first tests with the library in #4149.
Technically it works, but it's open to naming and implementation suggestions.

[twpayne]

Thanks @bakito! Let's discuss the implementation in #4149.