This modifies the GPluginGtkView into a stack, showing the list of plugins by default (called the 'overview'), or a page for a specific plugin. Going back and forth is automated, but an application can request the page for a plugin directly if needed.
The plugin row no longer expands to show details or shows a config button, but its activation goes to its own page now. This also makes each row a bit more balanced vertically, since there's no GtkRevealer taking up invisible space underneath.
The new plugin page is mostly a copy of the previous plugin row, except:

It's always expanded (or rather, it cannot be collapsed.)
The main details are re-arranged a bit to fit nicely on a page.
All information is found via GtkExpressions.
Instead of separate labels for each author/dependency, these are now a single newline-separated label, which is easier to generate.
Booleans display a check mark instead of text, like in the inspector.
Information labels are selectable and have a labelled-by relation.
The error message is allowed to wrap.

Settings, once implemented, can go at the end of this page.
I debated splitting the plugin info into a stack with 'important' vs 'developer-oriented' entries (somewhat how GtkAboutDialog splits its information), but that can go in a separate review if it's done.
NOTE: This deletes the expanded property from GPluginGtkPluginRow; that's probably an ABI break, though /r/1834 means it was never registered in a released version.

Opened the separate page of a few plugins, and saw that details were available. Also, the switch was in sync with the switch in the overview.