Remove gateway contract locations from Assets (#986)

* move trait for re-use

* fix mocks and tests

* fix clippy error

* move AllowSiblingsOnly to core

* update cumulus

* remove gateway from inbound channel

* remove uneeded function

* fix failing test

* fixed tests

* remove redundant clone

* updates inbound benchmark fixtures

* more fixes

* fix transfer token

* remove unused code

* update polkadot-sdk

* Enable bridge on start up

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Co-authored-by: claravanstaden <Cats 4 life!>