Update & Upgrade

[ferishili]

This PR fixes #6

Changes

• new moodle coding styles! e.g. array() to [], lang sorting, etc.
• core namespace changes: core_component to \core\component
• use LTI credentials from Opencast API tool plugin!
• Use the opencast API library instead of pure curl calls if necessary!
• Support for OC 16 more in the area of either eliminating the use of search endpoint or making it (backward) compatible.
• Upgrade behat test!
• Use the latest moodle ci workflows!

New Setting

• The setting related to LTI consumer key and secret are now removed from the plugin setting and has been replaced by a simple checkbox, which makes sure to Use LTI Authentication!
  The reason is to bring all credentials to one place (tool_opencast plugin) as it has been decided by the community. So we just use the LTI Credentials from Opencast API from now on!