Keyboard controls for workspace search

[tracygardner]

• Ctrl + F highlights matching items but there is no way to move focus to them
• Make tab work within workspace search to move between buttons
• Text on buttons in workspace search is not visible in dark themes:

@lawsie

• Allow Esc to close the workspace search and move focus to the currently selected block
• Should focus use the yellow focus highlight instead of the current colour approach? Decide and implement. @lawsie
• Make sure workspace scrolls correctly
• Add documentation. Include Enter and Shift+Enter for moving through results and Esc for closing search and moving focus @lawsie
• T should just go to first category in the toolbox, not the toolbox search
• Should Ctrl+F in the toolbox go to toolbox search instead of workspace search?
• Enter in toolbox search results should move to first block in results flyout?
• Should typing in the toolbox enter into the toolbox search? Should it be used to select a category? A combination? Design work needed

[tracygardner]

T should just go to first category in the toolbox, not the toolbox search: #359 (comment)

[tracygardner]

0e8dec2 stopping gizmos preventing propagation of Esc. So Esc now does move focus to the selected block, but it this intuitive?

[tracygardner]

#540 allows users to start typing the name of a category in the toolbox to move focus to that category. Supports opening of subcategories. This improves the UX for keyboard users when moving between categories that are far apart which takes a lot of up/down arrow key presses.

[tracygardner]

feeb145 makes it so that categories scroll into view in the toolbox when focuses by starting to type their name. E.g. moving from Scene to Snippets and back on a small/low res screen.