Make it easier to view reverse dependencies of projects without wheels

[jwodder]

Because projects without wheels are excluded from search and the "Browse Projects" list, it can be difficult to reach their pages in order to view their reverse dependencies (which is the only thing their pages offer other than a link to PyPI). At the moment, the only way to get to such a page is via either URL manipulation or by clicking on a link from a project that depends on them or in the reverse dependencies list of a project that they depend on.

Idea: Add a checkbox next to the project search input for also searching projects without wheels.