The next [runtime upgrade v0.4.0](https://zeitgeist.subsquare.io/council/motions/34) requires `polkadotXcm.safeXcmVersion` to be configured properly to be able to send XCM, as `pallet-xcm` uses the storage instead of a hard coded value from v0.4.0 onward.

Right now XCMv2 is deployed. The message format V1 is the oldest supported version, V2 is the current version. With v0.4.0, XCMv3 is deployed. The message format V1 will be deprecated, V2 will be the safe default and V3 will be the most recent version.

⚠ Not configuring this value before deployment of v0.4.0 results in the inability to send XCMs. 

 Add a registrar to the system.

 The dispatch origin for this call must be `RegistrarOrigin` or `Root`.

 - `account`: the account of the registrar.

 Emits `RegistrarAdded` if successful.

 # <weight>
 - `O(R)` where `R` registrar-count (governance-bounded).
 - One storage mutation (codec `O(R)`).
 - One event.
 # </weight>

- **Problem Statement:** 
  - Proper configuration of `polkadotXcm.safeXcmVersion` is crucial for sending XCM in the upcoming runtime upgrade v0.4.0.

- **Significance:** 
  - Failure to configure `polkadotXcm.safeXcmVersion` before v0.4.0 deployment will lead to the inability to send XCMs.

- **Proposed Solution:** 
  - Configure `polkadotXcm.safeXcmVersion` to ensure compatibility with the new XCMv3 message format in the upcoming runtime upgrade v0.4.0.

- **Expected Outcomes:** 
  - Ensuring proper configuration will enable the seamless sending of XCMs post the v0.4.0 upgrade.

#35 Set safe default XCM version to 2