Draft: Asyn multi-device

Refactor the asynPortDriver class to use a separate asyn address for each channel. This simplifies the implementation and the database files since we don't need to handle multiple copies of each channel parameter.

This is preparation for the AreaDetector conversion in !16

• Remove commits.cpp. Add methods in the asynPortDriver class for updating groups of parameters
• Restructure database files. Create a channel database that can be loaded for each channel with a unique prefix and asyn address
• Add snippets for module initialization and database loading