Turn Entry Page into Template
Removed a lot of unnecessary logic and NotImplemented values.
Instead of deleting all widgets depending of if they are shown on screen or not, they are just hidden and shown on demand.
Depends on !389 (closed), !313 (merged)
Together with !390 (merged) and !384 (merged) it would be easy to remove the ScrolledWindow class. Note that the search page do not require any special functionality of ScrolledPage.
This is required to port the app to GTK 4.
Closes #182 (closed)
Edited by Maximiliano