Fix a package problem in bluetooth discovery.

Move classes to ...fuchsia.bluetooth.discovery instead of ...fuchsia.bluetooth .
Add a proxies-utils module.

The proxies-module regroup a set of classes used to build generic proxies.
Add a bluetooth importer using generic proxies.
Big clean/restructuration of the project.

Update the module hierarchy and naming convention module, apply the changes to the
whole project.
Modification of all modules which wasn't respecting the naming convention.
Creation of base module for protocols that need it but not using it.