* Refs #2111, closes#2110
* New Context dataclass/subclass mechanism, refs #2127
* Define QueryContext and extract get_tables() method, refs #2127
* Fix OPTIONS bug by porting DaatbaseView to be a View subclass
* Expose async_view_for_class.view_class for test_routes test
* Error/truncated aruments for renderers, closes#2130
* Docs for permissions: in metadata, refs #1636
* Refactor default_permissions.py to help with implementation of #1636
* register_permissions() plugin hook, closes#1939 - also refs #1938
* Tests for register_permissions() hook, refs #1939
* Documentation for datasette.permissions, refs #1939
* permission_allowed() falls back on Permission.default, refs #1939
* Raise StartupError on duplicate permissions
* Allow dupe permisisons if exact matches