Decouple migration tasks for each component

So they are easier to reason about and also easier to move back into each component in [#61228518]

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Re-enable pending spec since [#55660590] was fixed

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Move Sandbox into Bosh::Dev::Sandbox

So it is easier to use outside of integration tests

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Introduce rake task to run sandbox outside of integration specs

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Move assets only used by sandbox into bosh-dev

[Finishes #61231410]

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Introduce RenderedTemplatesArchive model

Tracks rendered template archives for each instance for later clean up

[#60724646]

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>