Populate non-immutable collections directly on deserialize (dotnet/corefx#41482)

Populate non-immutable collections directly on deserialize (dotnet/corefx#41482)

* Populate non-immutable collections directly on deserialize

(rather than storing in temporary collections and using converters to
create and populate instances)

* Fix deserilizing nested dictionaries

* Don't get add method for types we can populate without reflection; fix failing tests

* Misc perf changes

* Additional changes

* More changes

* Address review feedback

* Address feedback

Commit migrated from https://github.com/dotnet/corefx/commit/2c06259cf2400704e550a74bf7b044159c2fcce5