MDL-41476 scorm admin settings & scorm12.js - added SCORM 1.2 compatability mode checkbox in scorm admin panel and changing CMIString length based on it

Adding SCORM 1.2 standard mode checkbox in scorm admin panel. By default it will be enabled and
its config name is `scorm12standard`, plugin name is `scorm` and value is `1`.
If `scorm12standard` is `1` CMIString256 is of length 256 and CMIString4096 is of length is 4096
if `scorm12standard` is `1` CMIString256 is of length 4096 and CMIString4096 is of length is 16384