[corlib] Move the implementations of virtual methods from Assembly to RuntimeAssembly to ease netcore integration. (#12805)
* [corlib] Move the implementations of virtual methods from Assembly to RuntimeAssembly to ease netcore integration.
* [corlib] Move more code to RuntimeAssembly.
* [corlib] Move fields from Assembly to RuntimeAssembly/AssemblyBuilder.cs. Reduce the amount of fields visible to runtime code.
* Update serialization tests.
* Fix the MOBILE build.
* Bump API snapshot submodule
12 files changed: