Move transforms structs into namespace Transforms

[CongMa13]

• Move transforms driver into namespace Transforms
• Move other transforms structs into namespace TransformsImpl

[cgmillette]

@CongMa13 Can we rebase this on the aos_soa_dev branch and target that branch? Looking at merging this to develop soon with #368

[CongMa13]

@cgmillette this PR has been rebased onto aos_soa_dev