refactor: propagate attrs & behavior with dict-like ak.Array input data

[pfackeldey]

Currently ak.Array (with dict input data) and ak.zip differ in the following ways:

1. ak.zip does broadcasting, ak.Array does not (it errors instead)
2. ak.zip does propagate attrs and behavior from all (nested) arrays in the given dictionary, ak.Array does not

For 1. this PR improves the error message for ak.Array if it encounters different length inputs to give a hint to try ak.zip instead (if broadcasting is a suitable solution).

The second difference does not exist anymore with this PR, ak.Array will now also propagate attrs and behavior in the same way ak.zip does. I think it is a bit unintuitive that ak.zip and ak.Array currently behave different for propagating attrs and behavior.

I'll add a policy label, because it might be good to hear some input/feedback from @ianna, @jpivarski and @agoose77 about this change.

(Closes: #3346)

[ianna]

Thanks! I think, a test would be nice to have along with these changes :-)

[ianna]

@pfackeldey - Thanks! please, merge it.