MDL-46051 mod_lti: Fixing errors in unknown_service_api_called class

Also adding unit tests.
MDL-46051 mod_lti: Not enough data passed to lti_extend_lti_services
MDL-46327 phpunit: drop_table should be used, rather then drop_temp_table
Merge branch 'wip-mdl-46327' of git://github.com/rajeshtaneja/moodle
MDL-46885 mod_forum: diverge version numbers

Before this patch the version number could dangerously clash with
27_STABLE increments - and miss the upgrade steps for MDL-1626
Normalize request header names.
Merge branch 'MDL-46051_LTI_event' of https://github.com/moodlerooms/moodle