Split and migrate origin/bridges-v2 branch

[bkontur]

origin/bridges-v2 contains dynamic lanes stuff, so we need to migrate it:

• relayer-relevant changes stays in bridges repo above master branch
• runtime-relevant changes goes to the polkadot-sdk repo above master branch

Possible solution 1:

• refactor origin/bridges-v2 so it reflects actual bridges master structure for relayer code
  • rebase or merge with latest master
  • remove all runtime-relevant code
  • origin/bridges-v2-relayer
• refactor origin/bridges-v2 so it reflects actual polkadot-sdk master structure for runtime code in ./bridges substree
  • migrate cleaned-up branch to the polkadot-sdk above actual master
    • remove or ignore relayer-related code
    • origin/bridges-v2-runtime

Possible solution 2:

• maybe just cherry-pick all commits from origin/bridges-v2 manually ignoring those with bumping crates