access-requests: improve styling

[ntarocco]

After requesting access to the restricted files, the user will receive an email with the link: https://<mydomain>/access-requests/verify?access_request_token=<token>

Here the page:

Users have to submit the request by themselves, using the "submit" button on the top right. After submitting the page looks like this:

This UX of this page requires more work. Template: invenio_app_rdm/requests_ui/templates/semantic-ui/invenio_requests/guest-access-request/index.html

[kpsherva]

fixed as part of https://github.com/inveniosoftware/invenio-rdm-records/issues/1395