Improve span copy of pointers and structs containing pointers (dotnet/coreclr#9999)

Improve span copy of pointers and structs containing pointers (dotnet/coreclr#9999)

Improve span copy of pointers and structs containing pointers

Fixes dotnet/coreclr#9161

PR dotnet/coreclr#9786 fixes perf of span copy of types that don't contain references

Commit migrated from https://github.com/dotnet/coreclr/commit/a6a7bde881a404fd3e44b2909960675072b4fca1