Catch BDM related InvalidBDM exceptions for server create v2.1

For v2.1 api, we should catch exception explicitly. There are some
BDM related InvalidBDM* exceptions missing catch. This patch fix this.
Also move the related unittests into block_device_mapping unittests.

Change-Id: Id1bef4adc71ffedd52eb9278b5d09954fc1b1193
Merge "Catch BDM related InvalidBDM exceptions for server create v2.1"