XCM-Simulator tests: Collectives

[ruseinov]

The goal of this issue is to convert zombienet-based integration tests as seen here into an xcm-simulator set of tests similar to this example..

How to approach

• Add cargo dev-dependencies for collectives runtime that import all the relevant runtimes for testing as git dependencies
• Replicate all the relevant XCM integration tests as unit-tests for said runtime
• Document those testing scenarios so that they could be used by the community as configuration and usage examples
• Make sure this runs in the CI