feat!: Introduce new focus tree/node functions.#8909

BenHenning merged 8 commits intoRaspberryPiFoundation:rc/v12.0.0RaspberryPiFoundation/blockly:rc/v12.0.0from

BenHenning:add-focus-manager-callbacks-and-improvementsBenHenning/blockly:add-focus-manager-callbacks-and-improvementsCopy head branch name to clipboard