Remove the "Frequent" tab on the Apps grid

The Frequent apps grid has a few problems:

• on a fresh install there would be no history of app usage so the applications shown in the grid have no relevance it takes time to be useful instead of being useful from the start
• the grid has far too many items in it to be relevant; 24 apps is well beyond the average use case as most people don't frequently use that many, so it gets populated with several apps that are single use (hello xterm)
• the position of items in the grid are always changing based on an unknown frequency metric (and not by user-intended input) which makes it a poor way to quickly launch apps as one would have to constantly learn the positions of the items in the grid
• having two app grids is a bit superfluous and needlessly complicates the app launching navigation: you have to spend time checking the frequent grid and if it's not there you have to switch over to another grid and find the app you need in there it's not straightforward.

By removing the frequent" tab we can simplify the overall navigation of the app grid by having a single grid we can focus on (that could have various ways of organization) in order to simplify and increase the usefulness of the app launching process , say by implementing custom ordering via drag and drop !603 (closed) perhaps 😉

/cc @aday @bertob @jimmac