Audit Fixes

[seunlanlege]

Implements fixes from the SRLabs audits

• [x] use saturating_add for dispatcher (ref https://github.com/Wizdave97/hyperbridge-audit/issues/8)
• [x] Use decode_with_limit in pallet-call-decompressor (ref https://github.com/Wizdave97/hyperbridge-audit/issues/3)
• [x] Add neccessary benchmarks and weights (ref https://github.com/Wizdave97/hyperbridge-audit/issues/4)