Statemint Reserve Asset Transfer

[apopiak]

This PR adds a FungiblesAdapter as an asset transactor to Statemint to allow for Reserve-based asset transfers of Statemint assets.

Todos

• Add the same config to Statemine and Westmint

[apopiak]

Config looks ok based on the xcm simulator test with a similar mock runtime here:
https://github.com/paritytech/polkadot/pull/3548/files#diff-0c1e73932c0f34b91c9dd40c479baa1f7550f4541ea15e74129f7fd94440da97R248

[KiChjang]

3 comments, but they all apply to the statemint and westmint XCM configs.

On another note, the syntax for the XCM config is arcane, I wonder if we can use some macro magic to solve it...?

[shawntabrizi]

this looks okay to me.

I assume we have tested this locally and all that?

Also an end to end test on westend when that is ready would be good

[apopiak]

this looks okay to me.

I assume we have tested this locally and all that?

Also an end to end test on westend when that is ready would be good

As mentioned it was tested via XCM sim. I've had issues getting it to test locally with Polkadot js apps due to types issues (with XCM) and was hoping an end-to-end test on Westend would be enough.
We also need to set up some integration tests in general.

[apopiak]

Tested this sufficiently to merge and then experiment more with a deployment on Westend.