XmlSerializer support for IsDynamicCodeSupported=false (#59386)

XmlSerializer support for IsDynamicCodeSupported=false (#59386)

* XmlSerializer support for IsDynamicCodeSupported=false

Add more checks to XmlSerializer to check the SerializationMode. Don't try to use Reflection.Emit if the SerializationMode is ReflectionOnly.

These changes were ported from
* https://github.com/dotnet/runtimelab/pull/593
* https://github.com/dotnet/runtimelab/pull/600

Fix #59167

* Fix a bug in XmlSerializer.CanDeserialize when in ReflectionOnly mode.

* Port UAP code for CanDeserialize

* PR feedback

* Add a linker test to ensure linker option '--enable-opt sealer' works when IsDynamicCodeSupported==false.