Add universal_viewer install task

[ghost]

The universal_viewer installation mechanism will change in version 3. This task allows those upgrading to install universal viewer.

@samvera/hyrax-code-reviewers

[ghost]

@no_reply follow on from #3761

[cjcolvar]

Is there enough duplication between this and

hyrax/lib/generators/hyrax/install_generator.rb

Lines 178 to 179 in 0e02c4a

	copy_file 'uv.html', 'config/uv/uv.html'
	copy_file 'uv-config.json', 'config/uv/uv-config.json'

that it might make sense to make the rake task the definitive declaration and have the generator call this rake task? That might also include removing the explicit call to yarn install and instead instruct the user to run it (in the puts on line 13).

[stale]

This issue has been automatically marked as stale because it has not had activity for 30 days. It will be closed if no further activity occurs within 14 days. Thank you for your contributions.

[cjcolvar]

@geekscruff This looks good. I think a rebase from master will downgrade valkyrie and take care of the failing bundle job in the circleci build.

[ghost]

@cjcolvar green :)