This updates the core_question_search_shared_banks external function
with additional parameters to make it applicable outside of the "Switch
bank" dialogue in the quiz, with the corresponding changes to the
question_banks_datasource Javascript module, and unit test coverage.
It also adds a new \core_question\output\question_category_selector
class for rendering a select list of question categories, migrating
the logic used in qbank_managecategories to a core namespace. There
is a fragment callback for rendering this via AJAX.
Mark Johnson
b9b69a5e3e