Make JSON support required properties (#72937)

Make JSON support required properties (#72937)

* Throw exception when 'required' keyword used but ctor does not have 'SetsRequiredMembers'

* Support required keyword (and internal IsRequired)

* remove local variable (forgot to press Save All)

* revert added namespaces in two files

* Apply feedback

* apply second round of feedback (minus HashSet optimization)

* Use BitArray rather than HashSet

* simplify validation code

* Truncate the message if too long, flip meaning of bit array bits

* remove default value, add description for BitArray

* for compiler attributes check for full type name rather than using typeof on net7.0