Add support for collectible types to SOS (#19842)

Add support for collectible types to SOS (#19842)

* Add support for collectible types to SOS

Collectible types indirectly reference managed LoaderAllocator via
pointer to native AssemblyLoaderAllocator stored in their MethodTable.
GC uses this relation when scanning object graph to determine which
objects are rooted and which ones are not.
The gcroot command in SOS doesn't understand this relation and so it
is unable to find all roots for LoaderAllocator.
This change fixes it.

* PR feedback

Make the failure to get the collectible info non-fatal to make it
compatible with older runtimes.