Throw an exception when passing strings by-value as out parameters. (#21513)

Throw an exception when passing strings by-value as out parameters. (#21513)

* Throw an exception when passing strings by-value as out parameters.

* Fix encoding

* Don't use override in this PR.

* Clean up Marshal_In

Marshal_In was copied back into existence from Marshal_InOut. Clean it up a bit.

* Remove extraneous whitespace.

* Fix failing test.

* Remove out attribute in COM string tests.

* Add back attribute and check for exception thow in COM tests.

* Add block comment to explain the implementation of Reverse_LPWStr_OutAttr in the NETServer.

* Only throw in a CLR->Native marshalling situation.

* Fix asserts from changed code-paths used in ILWSTRMarshaler.

* Add comment and explicitly load in a null value (instead of leaving it uninitialized).

* Apply suggestions from code review

Co-Authored-By: jkoritzinsky <jkoritzinsky@gmail.com>
Co-authored-by: Jan Vorlicek <janvorli@microsoft.com>