Further obscure communities UI

[cc-a]

• Issue: Make new deposits members of the ICL org by default #136

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This PR further obscures the communities feature in the web UI by:

• Updating "new upload" ui elements to href to /uploads/new?community=icl. This has the effect of pre-selecting the community into which the record will be submitted. This of course presupposes that a community with the identifier 'icl' exists. For the time being this must be created manually.
• Hiding the community header on the deposit form.
• Hiding a "new upload" element that was difficult to update in the event of a no results being returned on the user uploads list page.

Note this PR is based on the onboarding-docs branch (from #147) as wanted to make sure these further customisations were captured in the docs. I'll rebase it once #147 is merged.

Developer Checklist

Developers should review and confirm each of these items before requesting review

• Code meets acceptance criteria from issue
• Unit tests are written and all pass
• User Test Scripts (if required) are written and have been run through
• Code documentation and related non-code documentation has all been updated

Reviewer Checklist

Reviewers should review and confirm each of these items before approval
If there are multiple reviewers, this section can be duplicated for each reviewer

• Code meets acceptance criteria from issue
• Unit tests are written and all pass
• User Test Scripts (if required) are written and have been run through
• Code documentation and related non-code documentation has all been updated
• Migation has been created and tested

Testing

List user test scripts that need to be run

List any non-unit test scripts that need to be run