DPL: Add TableBuilder / TableConsumer for arrow

This introduces a new TableBuilder helper which allows creating
`arrow::Table` objects in a simple manner. For the moment the type of
each column has to be known at compile time, but it should be fairly
straightforward to make it dynamic.

Paired to that comes a TableConsumer which can be used to create
`arrow::Table` from a previously serialized `arrow::RecordBatch`.

DPL: add GUI to send signals to processes

Also add unit test for the device inspector GUI.

Fix segfaults of devices using non-standard completion policies

The bug was introduced in 'DPL: decouple GUI backend from drawing operations' and it affected f.e. o2DiamondWorkflow.

DPL: Treat unknown exceptions as errors

DPL: Treat unknown exceptions as errors

DPL: Treat unknown exceptions as errors

DPL: Treat unknown exceptions as errors

DPL: Treat unknown exceptions as errors

DPL: Treat unknown exceptions as errors

DPL: add StringContext to send around strings.