When using multiple instances of the same pallet, each instance was executed with the components of
all instances. While actually each instance should only be executed with the components generated
for the particular instance. The problem here was that in the runtime only the pallet-name was used to determine
if a certain pallet should be benchmarked. When using instances, the pallet name is the same for both of these
instances. The solution is to also take the instance name into account.

The fix requires to change the `Benchmark` runtime api to also take the `instance`. The node side is written in a backwards
compatible way to also support runtimes which do not yet support the `instance` parameter.

…p major'

Co-authored-by: clangenb <[email protected]>

Co-authored-by: Adrian Catangiu <[email protected]>