[RFC #0096] Rebaser should validate target data and update labels

[buildpack-bot]

Spec PR: buildpacks/spec#335

On Platform API 0.12 or greater, the rebaser must ensure the following metadata matches for the old and new run images:

• os (image config)
• architecture (image config)
• variant (image config, if specified)
• io.buildpacks.distribution.name (image config label, if specified)
• io.buildpacks.distribution.version (image config label, if specified)

These checks can be skipped if -force is passed (or CNB_FORCE_REBASE set)

The value of io.buildpacks.base.* labels SHALL be modified to that of the new run-image