Split compose_call into two functions

[haerdib]

closes #598

[masapr]

In the issue you say "in case multiple calls for one pallet are created, the current code is forced to get the PalletMetada each time for each call. That's not necessary."

I don't see, how you can create this scenario with the new macros. Would you call
let pallet_metadata = $node_metadata.pallet_by_name($pallet).unwrap().to_owned();
directly and then use the second macro to compose the calls?

Generally, I would propose to write a simple test, with the scenario described in #598. If it can be done nicely with the new code, then I'm fine with it.

[haerdib]

Added an unit test in 688068a. Is that what you imagined?

[masapr]

Added an unit test in 688068a. Is that what you imagined?

Yes. But I would also add some assertion on _call_one and _call_two.
... sorry for being so picky here. I know our code-base is not really written with TDD. But if we specifically change something for a specific purpose, why not check, that what we aim for, actually works.

[haerdib]

Cool! You're right - I fixed it in 5de32cf and moved it to the correct crate as well.

[masapr]

LGTM, thanks for the test :-)