Add an application metadata item for allowing ESM/EOL bases.

[lengau]

What needs to get done

An application should be able to opt into supporting ESM and EOL bases, but lifecycle commands should be gated on a --ack-unsupported-base option that allows building even on an unsupported base.

When an ESM/EOL base is used (and --ack-unsupported-base is passed) in a lifecycle command:

1. If the release is on old-releases.ubuntu.com, any overlay layers need to include this change. (Use Allow modifying existing default repositories craft-archives#176 for this)
2. In these cases, we tell craft-parts to allow unsupported releases with chisel (Add support for EOL bases with chisel craft-parts#1159).

We cannot rely on the system's (or our Ubuntu base's) ubuntu.csv file, but we can either use something like https://github.com/lengau/distro-support or vendor this same info as demonstrated in canonical/rockcraft#909

Why it needs to get done

Support for EOL releases in Rockcraft.

[syncronize-issues-to-jira]

Thank you for reporting your feedback to us!

The internal ticket has been created: https://warthogs.atlassian.net/browse/CRAFT-4637.

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