Lifecycle.supportsDynamicLoad

[jglick]

In CloudBees CI running in high availability mode we run a custom lifecycle (#8589) which is not compatible with the option to dynamically install a plugin. While an individual plugin can be marked on the update center as requiring a controller restart to install, this was not available generically for any plugin. Lifecycle seems like the right place for it since it already defined when and how to restart.

Testing done

Interactively tested inside CloudBees CI by overriding this method.

Proposed changelog entries

• N/A, beta-only API

Before the changes are marked as ready-for-merge:

Maintainer checklist

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3. Changelog entries in the pull request title and/or **Proposed changelog entries** are accurate, human-readable, and in the imperative mood.

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[MarkEWaite]

/label ready-for-merge

This PR is now ready for merge. We will merge it after approximately 24 hours if there is no negative feedback.

[timja]

/label ready-for-merge

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This PR is now ready for merge, after ~24 hours, we will merge it if there's no negative feedback.

Thanks!