Add synchronize parameter to alpaka PSet of Alpaka modules

[makortel]

Many developers of Alpaka modules add synchronize parameter to call alpaka::wait() at the end of acquire() / produce(). Having such parameter centrally would allow

• repeating some lines of boilerplate code
• have such a setting globally set in ProcessAcceleratorAlpaka (similarly to backend)
• EDMetadata would know at the Event insertion time all async work has finished