check use before defined in init exprs

[arezaii]

This updates how dyno detects use-before-definition errors. It should resolve https://github.com/Cray/chapel-private/issues/6666.

Fixing the missing error in Dyno updated the production error messages for use-before-define errors. Tests have been updated to reflect the changes.

A special case of use-before-defined for self-definition, has been added.
For example, given:

var f4 = f4 * 4;

the previous production error would be:

MyTestModule.chpl:1: In module 'MyTestModule':
MyTestModule.chpl:1: error: 'f4' used before defined
MyTestModule.chpl:1: note: defined here

The new production error will be:

MyTestModule.chpl:1: In module 'MyTestModule':
MyTestModule.chpl:1: error: statement references variable 'f4' before it is defined

and more detail can be viewed by compiling with --detailed-errors:

─── error in MyTestModule.chpl:1 [SelfDefinition] ───
  Statement references variable 'f4' before it is defined.
  In the following statement:
      |
    1 | var f4 = f4 * 4;
      |
  the variable 'f4' is used to define itself here:
      |
    1 | var f4 = f4 * 4;
      |          ⎺⎺
      |
  Variables cannot be used to define themselves.

Future work remains to specialize error messages for related cases when shadowing occurs. For example, the following codes exhibit self-definition and use-before-defined errors, respectively:

var x = 42;
{
  var x = 2 * x;
}

var y = 42;
{
  var x = 2*y;
  var y = 2*x;
}

It would be nice to indicate to users that the outer variables in each case are supplanted by the local definition of a variable by the same name.

TESTING:

• paratest [Summary: #Successes = 17740 | #Failures = 0 | #Futures = 898]
• gasnet paratest [Summary: #Successes = 17924 | #Failures = 0 | #Futures = 909]