MDL-39020 phpunit: Rename incorrect filename

Rename externallib_tests.php to externallib_test.php
Fix failing unit tests
MDL-37065 - Change get_string('status') token in assignment submissions page to a different token (for translation flexibility)

AMOS BEGIN
 CPY [status,core],[status,mod_assign]
AMOS END
MDL-40472: Clean all codechecker warnings on mod_assign
MDL-40369 theme: Fix core using deprecated icons
MDL-40369 theme: Remove deprecated icons
MDL-40369 theme: Afterburner does not override deprecated icons
MDL-40369 theme: MyMobile does not override deprecated icons
MDL-40369 theme: Removing old gif icons with PNG/SVG versions
MDL-40392 Navigation -> my courses listing tests

This introduces some behat tests to verify that
the display of enrolled courses in the navigation
block works as expected, both when a plain list
or a nested list is configured.

Personally I'm not happy with the way to select
expected text via css element. I'd love to see
something in an higher level like

I should see the text|link "xxxxx" in the "yyyy" "element"

with element being "block, header, footer, main...."

But that's another issue.
MDL-36479 quiz regrade: use progress bar to prevent time-outs
MDL-40443 setType notice in quiz reports.
MDL-40512 SCORM: prevent undefined warning
MDL-20867 LDAP NTLM fast path - allow FF to use NTLM when fastpath
enabled
MDL-39815 Add action to display the print windows on page load
MDL-39815 glossary mod: code improvement.
Use html_writer to print out divs.
MDL-39815: wiki and glossary mods: update print icon and system print popup
MDL-40496 deprecatedlib: remove 1.9 final deprecations
MDL-40516 deprecatedlib: final deprecation for old 1.9 functions

These functions have been throwing debugging notices for some time and
its time for them to be put to rest.
MDL-40466 libraries: Not deprecating get_sorted_contexts()
MDL-40527 enrol meta: respect $CFG->courselistshortnames

Thanks to James Henestofel for working this out in MDL-37558. That issue
got complex, so I am just submitting this simple part of it for
integration.