[1.0.50][feat] non-root redux subapp support

[gaganjakhotiya]

This change is to support a similar use-case as loadSubApp does here. If a reduxSubApp needs to be rendered within a composite component we won't be getting the DOM element to render the subapp in.

[CLAassistant]

All committers have signed the CLA.

[jchip]

Thanks for the PR. Can you provide some explanation on the context and use case for the change please?

[gaganjakhotiya]

This is to support a similar use-case as loadSubApp does here. If a reduxSubApp needs to be rendered within a composite component we won't be getting the DOM element to render the subapp in.