Add validation of segments when writing a `MultiRecord`

[briangow]

As mentioned in #555, when writing multisegment records we should validate the segments. A good initial step would be to simply add the already developed _check_segment_cohesion validation to the workflow.

There are likely a number of other validations that should be performed. For example, we may want to confirm that samps_per_frame is set for segments with expanded signals and that their length is as expected.

Please add any additional suggestions for validating the segments below.