WhenExpression Quote and Template validation

Parent issue: #335 Every plugin must be able to use all properties to construct the exact PSI element being fed in to achieve isomorphism between Quote and Scope. To ensure that AST parsing and our quote-and-template system is robust, more testing is needed to increase stability and reliability.

Checklist for WhenExpression

• Destructure and make available all methods related to rendering properties (no logic or PsiElements)
• Testing added for validation to ensure all properties can be used as a commutative identity.
• Ensure documentation is updated in Property matches the example in PropertyPlugin
• When confident about working unit tests, make sure WhenExpression is added to regression testing in QuoteTest.kt

Notes

• Feel free to place the target branch for the PR to quote-and-template-minor-cleanups