Use a separate controller action for full blame page view

We should consider extracting full blame page view into a separate Rails controller action to achieve better code-splitting. The full blame page with streaming adds an additional 85KB of javascript to the page. Right now both paginated and streamed versions of the page use a single controller action and thus we're loading a lot more code for the paginated view.

A new page should probably have a new URL with a proper redirect from a previous URL. The controller action could be called show_full. The streaming code should be placed into a new JS entrypoint for this page.

Availability and Testing

Regression testing, please make sure e2e:package-and-test job is passing.