Extend to C416 to dict comprehensions

[Skylion007]

Description

keys = range(100)
values = range(100)

out = {a:b for a,b in zip(keys, values)}

This is likely inefficient compared to the follow which does not need to unpack / repack the tuple.

out = dict(zip(keys, values))

This is essentially an extension of C416 to handle dict comprehensions as well. The version without the dict comprehension should be identical to the original code, just potentially more efficient.

[adamchainz]

Is zip required to be sure of this? Can't we suggest to rewrite more generally:

-{a: b for a, b in _}
+dict(_)

For any _ ? I think so...

Would you like to work on a PR here?

[Skylion007]

@adamchainz Yep, any iterable would work. This was easier to add than I thought: #490