Respect interval start & end side on ack

[Abe27342]

Description

Users of IntervalCollection can specify a start and end side when adding or changing an interval. Doing so changes the behavior for the resulting start and end local references put into the merge tree: using the default Side.Before causes references to slide forward when the segment they exist on is removed, whereas using Side.After causes references to slide backward.

In the common case, local reference positions sliding is initiated by removing a segment in merge-tree. However, IntervalCollection also reuses this slide logic when intervals are changed/added concurrently to a segment removal. This latter case did not correctly plumb through the sliding preference to the helper function it used, which gave undesirable merge semantics.

Resolves AB#22191.

[msfluid-bot]

Code Coverage Summary

↑ packages.dds.sequence.src:
Line Coverage Change: 0.01%    Branch Coverage Change: No change

Metric Name	Baseline coverage	PR coverage	Coverage Diff
Branch Coverage	89.47%	89.47%	→ No change
Line Coverage	89.74%	89.75%	↑ 0.01%

---

Baseline commit: 522f76f
Baseline build: 303346
Happy Coding!!

Code coverage comparison check passed!!

[msfluid-bot]

⯅ @fluid-example/bundle-size-tests: +297 Bytes

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	464.62 KB	464.68 KB	⯅ +61 Bytes
azureClient.js	562.79 KB	562.83 KB	⯅ +49 Bytes
connectionState.js	724 Bytes	724 Bytes	■ No change
containerRuntime.js	262.21 KB	262.22 KB	⯅ +14 Bytes
fluidFramework.js	406.75 KB	406.77 KB	⯅ +14 Bytes
loader.js	134.17 KB	134.18 KB	⯅ +14 Bytes
map.js	42.71 KB	42.71 KB	⯅ +7 Bytes
matrix.js	148.54 KB	148.54 KB	⯅ +7 Bytes
odspClient.js	528.73 KB	528.78 KB	⯅ +49 Bytes
odspDriver.js	97.84 KB	97.86 KB	⯅ +21 Bytes
odspPrefetchSnapshot.js	42.81 KB	42.82 KB	⯅ +14 Bytes
sharedString.js	164.73 KB	164.76 KB	⯅ +33 Bytes
sharedTree.js	397.21 KB	397.22 KB	⯅ +7 Bytes
Total Size	3.33 MB	3.33 MB	⯅ +297 Bytes

---

Baseline commit: 522f76f

Generated by 🚫 dangerJS against 8e187b5