feat(pool): allow staked senders to have multiple UOs in best_operations

[dancoombs]

Closes #251

Proposed Changes

• Simple change to allow staked accounts to have multiple UOs when calling best_operations on the pool. No changes were needed in the builder to allow for multiple UOs from the same sender in a bundle.
• Tested this by staking a sender on Arb Sepolia and sending 10 UOs (bundler in manual mode to force them all into a single bundle). Transaction here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.13%. Comparing base (b39116b) to head (c8f0678).

Additional details and impacted files

Files	Coverage Δ
crates/pool/src/mempool/uo_pool.rs	94.79% <100.00%> (+0.05%)	⬆️

Flag	Coverage Δ
unit-tests	54.13% <100.00%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
rundler binary	0.00% <ø> (ø)
builder	45.37% <ø> (ø)
dev	0.00% <ø> (ø)
pool	64.44% <100.00%> (+0.06%)	⬆️
provider	16.10% <ø> (ø)
rpc	25.67% <ø> (ø)
sim	77.86% <ø> (ø)
tasks	∅ <ø> (∅)
types	65.45% <ø> (ø)
utils	18.28% <ø> (ø)

[dancoombs]

Closing in favor of #732