Initial work on plugin details page for design/UX feedback

[nataliecarey]

I've gone through the designs to implement the features as I think they should be according to the designs.

Some example URLs (assuming this branch is running on port 3000:

• http://localhost:3000/manage-prototype/plugin/hmrc-frontend (a complete "included in this plugin" section)
• http://localhost:3000/manage-prototype/plugin/govuk-frontend (a plugin with no info provided)
• http://localhost:3000/manage-prototype/plugin/jquery (a plugin with only a description)
• http://localhost:3000/manage-prototype/plugin/%40hmcts%2Ffrontend (a really old last updated date)