JJ.Framework.Exceptions rework

[jjvanzon]

2019-05-02

Might split up in multiple tasks in the future. Some things may already be done.

• ~ New overload: ValueNotSupportedException(new { customerNumber }) to generate
  "customerNumber value '1234' not supported."
  Currently you can only do an object value whose type is used, which would give you: "string value '1234' not supported.", which is less meaningful.

  string flag;
  throw new Exception($"{nameof(flag)} '{flag}' not supported.");

• ~ Adding actual value to the comparison exceptions?
• ~ Making exception messages more like 'cannot be null' rather than 'is null'?