[MC-189700] The Search Items tab of the creative inventory is always in focus and cannot be deselected

The text box in the creative mode "Search Items" tab cannot be deslected, making it always focussed for the player. This will put any key press the player enters into the search bar, disallowing the player to opt out of this behavior in any way by deselecting the search bar. This is also irregular behavior when compared to other search bars like the social interactions screen, and the crafting recipe book which both can be intentionally deselected by clicking on buttons, or items.

Steps to Reproduce:

In creative, open your inventory
Go to the "Search Items" tab
Enter any text into the box
(Works as expected)
Left or right on one of the following:
1. An empty slot
2. A filled slot
3. The outside of the GUI

Observed Behavior:

No matter what the player presses, their focus will always be kept on the search bar box. Because of this, any key presses which have functionality (like the number keys MC-189975, or F key for the off hand) will not function as expected.

Expected Result:

When the player clicks on something that isn't the search bar itself, the focus would be lost. The player would be able to choose when they want to enter text, instead of always being allowed/forced to.