This patch removes the template parameter of the
`ClauseProcessor::processMotionClauses()` method and instead processes
both `TO` and `FROM` as part of a single call. This also enables moving
the implementation out of the header and makes it simpler for a
follow-up patch to potentially refactor `processMap()`,
`processMotionClauses()`, `processUseDeviceAddr()` and
`processUseDevicePtr()`, and minimize code duplication among these.