MDL-29070 enrol_enterprise: Code cleanup

In preperation for new features.
MDL-29070 enrol_enterprise: fix whitespace
MDL-29070 enrol_enterprise: coding style fixes:

* Declare method visibility
* Don't have variable names with underscores
* Comments without .
* if/for loop spacing
* Unused variables
* Split long lines
* Removed outdates files
MDL-29070 enrol_imsenterprise: moodlecheck warnings
MDL-29070 enrol_imsenterprise: code checker warnings