allow setting multicircuit names from run method

[splch]

Summary

can do:

multi_result = backend.run([qc_1, qc_2], name="multi-circuit").result().get_counts()

Details and comments

when running many jobs, concatenating child circuit names wont scale. this lets you set a short name

[Cynocracy]

Can you add a test case demonstrating what you mean? This seems to allow you to override every circuit name in the passed arguments, is that what you want?

[splch]

Can you add a test case demonstrating what you mean? This seems to allow you to override every circuit name in the passed arguments, is that what you want?

yeah i shouldve made this a draft pr - ill add some tests once it's working :)