add split-init error when uninitialized var used as actual

[arezaii]

This adds detection of an uninitialized variable used as an actual to a non-out formal. The previous error was a generic failure to resolve function [NoMatchingCandidates] and this improves the message by indicating that the candidate did not match because of the uninitialized actual passed to a non-out formal.

resolves https://github.com/Cray/chapel-private/issues/6624

Example program:

proc fn(const arg) {
  arg;
}
proc main() {
  var x;
  fn(x);
  x=5;
}

in production this produces the following error message:

MyTestModule.chpl:9: In function 'main':
MyTestModule.chpl:10: error: 'x' is not initialized and has no type
MyTestModule.chpl:10: note: cannot find initialization point to split-init this variable
MyTestModule.chpl:11: note: 'x' is used here before it is initialized

previous error message compiling with chpl MyTestModule.chpl --dyno --detailed-errors:

─── error in MyTestModule.chpl:11 [NoMatchingCandidates] ───
  Unable to resolve call to 'fn': no matching candidates.
       |
    11 |   fn(x);
       |
  
  The following candidate didn't match because an actual couldn't be passed to a formal:
      |
    6 | proc fn(const arg) {
      |         ⎺⎺⎺⎺⎺⎺⎺⎺⎺
    7 |   arg;
    8 | }
      |
  The formal 'arg' expects a value of type '?', but the actual was a value of type 'UnknownType'.
       |
    11 |   fn(x);
       |      ⎺
       |

Updated error message with -dyno --detailed-errors:

─── error in MyTestModule.chpl:11 [NoMatchingCandidates] ───
  Unable to resolve call to 'fn': no matching candidates.
       |
    11 |   fn(x);
       |
  
  The following candidate didn't match because an actual couldn't be passed to a formal:
      |
    6 | proc fn(const arg) {
      |         ⎺⎺⎺⎺⎺⎺⎺⎺⎺
    7 |   arg;
    8 | }
      |
  The actual 'x' expects to be split-initialized because it is declared without a type or initialization expression here:
       |
    10 |   var x;
       |       ⎺
       |
  The call to fn occurs before any valid initialization points:
       |
    11 |   fn(x);
       |      ⎺
       |
  The call to 'fn' cannot initialize 'x' because only 'out' formals can be used to split-initialize. However, 'x' is passed to formal 'arg' which has intent 'const'.

updated error message with --dyno --no-detailed-errors

MyTestModule.chpl:9: In function 'main':
MyTestModule.chpl:11: error: unable to resolve call to 'fn': no matching candidates
MyTestModule.chpl:1: In module 'MyTestModule':
MyTestModule.chpl:6: note: the following candidate didn't match because an actual couldn't be passed to a formal
MyTestModule.chpl:9: In function 'main':
MyTestModule.chpl:11: note: The actual 'x' expects to be split-initialized because it is declared without a type or initialization expression here

TESTING:

• paratest [Summary: #Successes = 17676 | #Failures = 0 | #Futures = 891]
• gasnet paratest [Summary: #Successes = 17857 | #Failures = 0 | #Futures = 900]