bluetooth: host: CS support for remote capabilities and FAE table

Adds HCI support for:
- LE CS Read Remote Supported Capabilities
- LE CS Read Remote FAE Table

Callbacks have been added to the conn object to allow upper layers to
make use of the cache commands, with which it will be possible to store
this information and provide it again in the case of a disconnect
and reconnect to the same device.

Signed-off-by: Olivier Lesage <olivier.lesage@nordicsemi.no>