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. 

Schedule a majority-carries referendum to be tabled next once it is legal to schedule
an external referendum.

The dispatch of this call must be `ExternalMajorityOrigin`.

- `proposal_hash`: The preimage hash of the proposal.

Unlike `external_propose`, blacklisting has no effect on this and it may replace a
pre-scheduled `external_propose` call.

Weight: `O(1)`

Set a safe XCM version (the version that XCM should be encoded with if the most recent
version a destination can accept is unknown).

- `origin`: Must be Root.
- `maybe_xcm_version`: The default XCM encoding version, or `None` to disable.

- **Problem Statement:** 
  - Proper configuration of `polkadotXcm.safeXcmVersion` is crucial for sending XCM in the upcoming runtime upgrade v0.4.0.
- **Significance:** 
  - Failure to configure this value before the v0.4.0 deployment will lead to the inability to send XCMs.
- **Proposed Solution:** 
  - Configure `polkadotXcm.safeXcmVersion` to enable XCM sending in the upcoming runtime upgrade v0.4.0.
- **Expected Outcomes:** 
  - Ensuring proper configuration will prevent issues with sending XCMs and maintain functionality post-upgrade.

#35 Set safe default XCM version to 2