* Update to new linker custom steps API
* PR feedback
- Fix indentation
- Add Initialize(LinkContext) to ExceptionalMarkHandler
- Remove unnecessary ifdef
- Use IsSetter/IsGetter
- Use [0] instead of Single()
- Avoid allocating empty collections
* Note override issue
* Clean up comments
* Move `DynamicRegistrationSupported` change earlier, along with the
detection code.
This solve the issue that `ILLink` does a similar job _before_ we have
the chance to disable the dynamic registrar.
* ILLink does not support considering other attributes as `[Preserve]`
when it is itself preserved at the assembly-level.
This ignored test is checking that feature so it cannot be enabled
for `NET`
Added to known breaking changes https://github.com/xamarin/xamarin-macios/issues/8900
* Fix removal of the dynamic registrar on legacy
* Fix IntPtr size inlining
Co-authored-by: Sebastien Pouliot <sebastien.pouliot@microsoft.com>