Fix/gateway message processing

[cdamian]

Description

Various fixes for LP gateway-related logic.

Changes and Descriptions

LP Gateway

• Make MessageProcessor implementation transactional to ensure that storage changes are reverted on failure.
• Move iteration over inbound sub-messages in execution logic.
• Add session ID check for inbound message entries when checking for votes/proofs.
• Use defensive weight when executing message recovery.
• Add more tests that cover session ID changes and storage rollback.

LP Gateway Queue

• Remove extra weight check.
• Get MessageQueue keys, order them, and iterate over them when servicing the MessageQueue.

Checklist:

• [x] I have added Rust doc comments to structs, enums, traits and functions
• [x] I have made corresponding changes to the documentation
• [x] I have performed a self-review of my code
• [x] I have added tests that prove my fix is effective or that my feature works

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 76.66667% with 14 lines in your changes missing coverage. Please review.

Project coverage is 48.41%. Comparing base (927af06) to head (731577f). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../liquidity-pools-gateway/src/message_processing.rs	70.00%	6 Missing :warning:
pallets/liquidity-pools-gateway-queue/src/lib.rs	82.14%	5 Missing :warning:
pallets/liquidity-pools-gateway/src/lib.rs	75.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1991 +/- ## ========================================== + Coverage 48.28% 48.41% +0.13% ========================================== Files 183 183 Lines 13406 13412 +6 ========================================== + Hits 6473 6494 +21 + Misses 6933 6918 -15 ```

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