Feature Request: Allow searching and matching apps using appdata metadata keywords

[nekohayo]

• My proposal does not exist in the PLANNED & NOT PLANNED.md document
• I have not found any other opened issues on the same feature request
• I believe this fits within Warehouse's scope of Flatpak management

Describe the feature idea in detail

It seems Warehouse does not search the appstream metadata keywords entries (example implementation here).

As such, if, in the "Install packages" section of the app, you search for such keywords, you won't get the relevant results:

• "webdav", "calendaring" or "reminders": you won't find GNOME Calendar
• "profiler" or "profiling": you won't find Sysprof nor GNOME Builder
• "debugger": you won't find GNOME Builder

GNOME Software does find these apps with those keywords.