RFC 14: Improve locking mechanism for parachains (#1290)

* rfc14

* Update polkadot/runtime/common/src/paras_registrar/mod.rs

Co-authored-by: Bastian Köcher <[email protected]>

* Update polkadot/runtime/common/src/paras_registrar/mod.rs

Co-authored-by: Bastian Köcher <[email protected]>

* Update polkadot/runtime/common/src/paras_registrar/mod.rs

Co-authored-by: Bastian Köcher <[email protected]>

* fmt

* fix

* Update polkadot/runtime/common/src/paras_registrar/migration.rs

Co-authored-by: Oliver Tale-Yazdi <[email protected]>

* fmt

* 2224 is unlocked

* update migration list

* update comment

* use VersionedMigration

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Co-authored-by: Bastian Köcher <[email protected]>
Co-authored-by: Oliver Tale-Yazdi <[email protected]>