[lib] Move SWMansion.react to lib so it can be shared across web and landing

Summary:
So we can move ConnectedWalletInfo in a subsequent diff... plus it just makes sense for this to be shared.

Depends on D6637

Test Plan:
We will see if web continues to look right after moving SWMansion.react component to lib.

EDIT: Things continue to look as expected:

Reviewers: ashoat, tomek, ginsu, rohan

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D6638