MDL-45565 core_message: Fixed strangers array

Strangers get mixed with noreply user and support user,
if  noreply/support users real user.
To avoid duplication use userid as array index. Also,
avoid fetching data again for noreply and support users,
if they are real users, then data is already feteched.
MDL-45565 core_message: Added unit tests.
MDL-45544 events: Add event user_profile_viewed trigger to user/profile.php.
MDL-45565 core_message: Reset internal users in phpunit
MDL-45565 phpunit: Changed testsuite_name, so as to avoid class collision
Merge branch 'MDL-45544-master' of git://github.com/lameze/moodle
MDL-45503 upgrade: add v2.7.0 sep lines
Merge branch 'wip-mdl-45565' of https://github.com/rajeshtaneja/moodle
MDL-45654 cron: fixed dataprovider timestamp issue
MDL-45698 behat: Added extra setting, to avoid timout issue
MDL-45698 behat: Fixed behat and symfony versions
Merge branch 'wip-mdl-45698' of https://github.com/rajeshtaneja/moodle
MDL-44871 Behat: Add step for selecting text in an editor
MDL-44871 Atto Bold: Add behat test
MDL-44871 Atto Accessibility Checker: Add behat test
MDL-44871 Atto Accessibility helper: Add behat test
MDL-44871 Atto Alignment plugin: Add behat test
MDL-44871 Atto Charmap: Add behat test
MDL-44871 Atto Clear Button: Add behat test
MDL-44871 Atto collapse plugin: Add behat test