Bluetooth: split setting params and enabling advertising (1/3)

Proper order of commands when starting advertising:
* set parameters
* set data
* enable advertising

This cannot be achieved when setting advertising parameters and enabling
advertising is put together in one function. Enabling before setting
data might cause first advertisements to be empty. If a device with
hardware filter pick up such advertisement, it might fail to properly
recognize our device.

Bug: 30622771
Bug: 19372779

Change-Id: I66c71f1b2c07c832eda0983ead816741798e923b