Acceptance tests adjustment

This adjustment consists of:

• A behat step to verify that a help page opens when clicking the respective help link (Admin doc and Instructor doc) in the block.
• Adjusting the Add block 005 scenario in the Add block feature to use the step.
• Changing the lang string identifier 'instrhelplabel' to 'instructorhelplabel'.
• Adjusting the block get content method to use the new lang string identifier.

Notes:

• The new behat step relies on config settings in config.php for the target windows and content to look for.
• The config settings are:
  • $CFG->behat_mhaairs_adminhelp_window_name = '__mhaairs_adminhelp_window';
  • $CFG->behat_mhaairs_adminhelp_window_content = 'Tegrity Help Portal';
  • $CFG->behat_mhaairs_instructorhelp_window_name = '__mhaairs_teacherhelp_window';
  • $CFG->behat_mhaairs_instructorhelp_window_content = 'Help Portal';
• If either the window name or window content is not defined for a target help page the step throws SkippedException.
• This settings can be changed whenever MGE change the help links.
• For backwards compatibility with pre 3.0 versions,