MDL-45192 assign: added behat script & new definitions to handle alert dialog

The behat script is to test the batch action to lock and unlock submissions.
The new definitions are to prevent the "unexpected alert open" error in Selenium.
MDL-45192 behat: Replacing specific-selector steps by a generic one

Having a I click on we can use all our selectors rather
than having multiple steps for the same purpose. This
step allow us to manage JS native dialogues without
having to fail a scenario.

Credit for Mohamed Alsharaf.
MDL-45607 events: changed the context passed to the user_profile_viewed event
MDL-45623: Fix assigned users count on role delete confirmation page
MDL-45629 mod_assign: removed use of '$this->objectid' in the submission_status_viewed event
MDL-45650 events: ensure correct objectid passed when triggering user_profile_viewed event
MDL-45654 cron: fix non-empty directories deletion

Remove errors when attempting to delete non-empty directories when
child directories do not get removed since the mtime was updated when
files were removed from the child directory.
Automatically generated installer lang files
MDL-45536 atto_html: Update the textarea size when switching to HTML view
MDL-45239 editor_atto: On Android do not restore focus in the callbackWrapper

It seems that Android automatically focuses the cursor in the last position
when the content editable region is programatically re-focused.

Whilst this does not cause an issue on it's own, when combined with the
behaviour of the dictionary auto-completion to restore focus on the start
of the word when a word has not yet been finished, this was causing us to
change focus when pressing buttons.
Merge branch 'MDL-45239-master-3' of git://github.com/andrewnicols/moodle
MDL-42526 mod_assignment : fix record insert with assigment.id 0
MDL-44014 Navigation: Set the correct context when retrieved via AJAX
Merge branch 'install_master' of https://git.in.moodle.com/amosbot/moodle-install
weekly on-sync release 2.8dev
MDL-45660 question statistics: make comparison more robust.
MDL-45676 mod_data: added missing additional name fields
MDL-45635 javascript: Make core dialogue translatable
MDL-45688 added missing library requirement
MDL-45686 qtype_multichoice get_num_selected_choices return wrong result