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

Adding SCORM 1.2 standard mode checkbox in scorm admin panel. By default it will be enabled
(i.e: config name = `scorm12standard`, plugin name = `scorm`, value = `1`)
If `scorm12standard` is `1` CMIString256 is of length 256 and CMIString4096 is of length is 4096
if `scorm12standard` is `0` CMIString256 and CMIString4096 are of length is 64000