While this change is not 100% required now, it's good habit
and we are checking for it since Moodle 4.4.
All the changes in this commit have been applied automatically
using the moodle.PHPUnit.TestReturnType sniff and are, exclusively
adding the ": void" return types when missing.
Improve login page worklow.
This patch improves the display and UX when a user provides
their second factor during the login process. It includes
refactoring the display to use a template fed by renderer.
In this commit, there are couple of fixes based on the report:
1. Removed legacy polyfill from provider.php
2. Fixed phpunit warning detected by CodeChecker
3. Removed unused files
4. Fixed the PHPunit failures by removing "securityquestions"
from the data_provider due to it has not been included as one of the factors
5. Added PHPunit test to the factors that can be unittested
6. Removed !important rule from tool_mfa/styles.css
7. Added (int) type to sleep method within sleep_timer method due to a php deprecation
in too_mfa/classes/manager.php
8. Changed last param form bool to string in not_enough_factors() when initiating
a new single_button object in tool_mfa/renderer.php
9. Add explanation text to login page
10. Fixed "Access to an undefined property .." from PHPStan
12. Fixed all the "Variable $.. might not be defined" from PHPStan
13. Fixed the issue from https://github.com/catalyst/moodle-tool_mfa/issues/379