Plugins: search should use no-results component and show non-installed matching plugins

[v18]

Reported by @rickybanister: Currently we display this when a search of installed plugins yields no results:

Here's what it looks like when searching all plugins:

Instead we should refactor to use the no-results component which looks like:

We will need a plugin-related svg for the image. Perhaps using the plugin gridicon in a circle? cc @MichaelArestad

I think there's also an opportunity here to add a button to the no-results text that submits the query to the plugin browser.

This is related to #830 - show non-installed plugins as suggestions for installed plugin search

[rickybanister]

I'm thinking about an image for this, but in the meantime I think you can use it without passing an image.