MaxIdentifierLength deprecation message gives no alternative

[tkutz]

The warning does not really help as it does not say what else to choose.

• Add hint for CShortIdentifier annotation (as already done in documentation)
• Remove "null" from message
• Remove the option from example in hover documentation
• Attach the warning to the parameter itself
• Add this warning also to CPP generator? @BeckmaR that is missing right?

[andreasmuelder]

Partly fixes in https://github.com/Yakindu/statecharts/pull/2210

done:

• remove null
• attach the warning to the parameter itself