Moves various legacy contracts into the legacy folder. Purpose of the
legacy folder is to explicitly mark the contracts that we're trying to
push users away from. By moving these contracts into the legacy folder,
we're creating a clearer message that users should be using alternatives
and should not be using these contracts after Bedrock.
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>