[XCM] Review XCM configs

[bkontur]

Relevant runtimes:

• For Westend: https://github.com/paritytech/polkadot-bulletin-chain/tree/main/runtimes/bulletin-westend (please create separate PR)
• For Polkadot: Add polkadot bulletin parachain #164 (adjust this PR or the PR on the top of that)

TODO

• both bulletin-westend and bulletin-polkadot-parachain should support only DOT ReseveBased transfer up/down with AssetHub, so no teleports
  • make sure we have some simple runtime tests for that (do not accept teleports, ...)
• Anything else? Both parachains won't be system parachains, just normal paras.