[OJS, OMP] Allow reviewers to indicate availability

Describe the problem you would like to solve
From issue #3017:

Provide reviewers with an option to indicate their temporary unavailability (which would also make themselves invisible to editors for selection) for a specific time period.

This could be added to the user’s Profile page.

This could be more generally useful for other roles (copyeditors, section editors, layout editors, proofreaders, etc.).

This would apply to OJS and OMP.

Describe the solution you’d like

  • Add a field to the user profile indicating when they will become available again (“Unavailable until…”)
  • Add a similar field to the review response process indicating a reviewer to specify unavailability when declining/accepting a request
  • Indicate to editors when searching for reviewers that particular accounts may be unavailable.

Alternately, investigate whether 3rd-party reviewer databases contain this metadata in a way that could permit OJS installations to benefit from centralized data.

Who is asking for this feature?

Additional information
The challenge with this feature will be ensuring that enough reviewers use and benefit from the feature in order to make development worthwhile. It seems unlikely that reviewers will log into OJS journals that include them as reviewers in order to proactively indicate that they are unavailable; this is possibly less of an issue for SaaS workflow tools, where a single field would apply to all the journals hosted by that platform.

Suggestions for how to overcome this issue (or motivating examples countering its assumptions) would be welcome!