[Runtime] Bound XCMP queue (#3952)
Re-applying #2302 after increasing the `MaxPageSize`.
Remove `without_storage_info` from the XCMP queue pallet. Part of
https://github.com/paritytech/polkadot-sdk/issues/323
Changes:
- Limit the number of messages and signals a HRMP channel can have at
most.
- Limit the number of HRML channels.
A No-OP migration is put in place to ensure that all `BoundedVec`s still
decode and not truncate after upgrade. The storage version is thereby
bumped to 5 to have our tooling remind us to deploy that migration.
## Integration
If you see this error in your try-runtime-cli:
```pre
Max message size for channel is too large. This means that the V5 migration can be front-run and an
attacker could place a large message just right before the migration to make other messages un-decodable.
Please either increase `MaxPageSize` or decrease the `max_message_size` for this channel. Channel max:
102400, MaxPageSize: 65535
```
Then increase the `MaxPageSize` of the `cumulus_pallet_xcmp_queue` to
something like this:
```rust
type MaxPageSize = ConstU32<{ 103 * 1024 }>;
```
There is currently no easy way for on-chain governance to adjust the
HRMP max message size of all channels, but it could be done:
https://github.com/paritytech/polkadot-sdk/issues/3145.
---------
Signed-off-by: 
Oliver Tale-Yazdi <[email protected]>
Co-authored-by: 
Francisco Aguirre <[email protected]>