(Offline follow-ups) Various improvements around pending state manager and outbox

[markfields]

Description

WIP - Dumping ground for a few random improvements I'm wanting to make in parallel to other changes.

Reviewer Guidance

WIP Draft

[msfluid-bot]

⯅ @fluid-example/bundle-size-tests: +413 Bytes

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	460.2 KB	460.28 KB	⯅ +77 Bytes
azureClient.js	558.17 KB	558.25 KB	⯅ +91 Bytes
connectionState.js	680 Bytes	680 Bytes	■ No change
containerRuntime.js	260.96 KB	261.01 KB	⯅ +56 Bytes
fluidFramework.js	400.53 KB	400.54 KB	⯅ +14 Bytes
loader.js	134.24 KB	134.25 KB	⯅ +14 Bytes
map.js	42.44 KB	42.44 KB	⯅ +7 Bytes
matrix.js	146.59 KB	146.59 KB	⯅ +7 Bytes
odspClient.js	525.47 KB	525.56 KB	⯅ +91 Bytes
odspDriver.js	97.72 KB	97.74 KB	⯅ +21 Bytes
odspPrefetchSnapshot.js	42.78 KB	42.79 KB	⯅ +14 Bytes
sharedString.js	163.28 KB	163.29 KB	⯅ +7 Bytes
sharedTree.js	390.99 KB	391 KB	⯅ +7 Bytes
Total Size	3.3 MB	3.3 MB	⯅ +413 Bytes

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Baseline commit: ab54977adb80af50f53378f4030903498deac464

Generated by :no_entry_sign: dangerJS against 6a59b2b8f4fedacacfc09e08a8184d0783400f4a

[microsoft-github-policy-service[bot]]

This PR has been automatically marked as stale because it has had no activity for 60 days. It will be closed if no further activity occurs within 8 days of this comment. Thank you for your contributions to Fluid Framework!