Add test cases for C++20 features

[LegalizeAdulthood]

• Concepts introduce new syntax:
  • Rename
• Modules introduce new syntax:
  • Rename
• Designated initializers introduce new syntax:
  • Rename
• Range for loop syntax enhanced:
  • Rename
• Lambda improvements:
  • Rename
• String literals as template parameters:
  • Rename
• Coroutines:
  • Rename
• using for scoped enums:
  • Rename
• constinit keyword:
  • Rename
• consteval keyword:
  • Rename
• spaceship operator <=>:
  • Extract Constant
  • Extract Function/Method
  • Extract Parameter
  • Extract Variable
  • Inline Variable
  • Move Implementation
  • Rename
  • Simplify boolean expression?
  • Split Variable