refactor(tree) use separate cells ids for src and dst cells in moves

[yann-achard-MS]

Description

Before this PR, we used to use assign the same identifiers to cells emptied by a move's detach and cells filled by a move's attach.
This is a problem because, when such a move is rolled back, the inverse move would keep those cell IDs the same, leading to a situation where different cells had been assigned the same identifier over time. This is an unnecessary complication that may cause bugs.

This PR allocates separate IDs for source and destination cells (using sequential IDs for neighboring cells).
The ID associated with the overall move (which is used to link the source and destination marks) gets assigned the same ID as the detached cell (except when the detach comes with an override).

Breaking Changes

None. The way edits are processed has not changed.

[alex-pardes]

Do you think it makes more sense to call this moveId instead of detachCellId, since the fact that it's the ID of the detach cell isn't relevant to the move in?

[yann-achard-MS]

Yeah, that's a good point. Thanks for pointing that out.

[msfluid-bot]

⯅ @fluid-example/bundle-size-tests: +226 Bytes

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	453.96 KB	453.96 KB	■ No change
azureClient.js	551.21 KB	551.21 KB	■ No change
connectionState.js	680 Bytes	680 Bytes	■ No change
containerRuntime.js	257.82 KB	257.82 KB	■ No change
fluidFramework.js	356.75 KB	356.86 KB	⯅ +113 Bytes
loader.js	132.91 KB	132.91 KB	■ No change
map.js	41.43 KB	41.43 KB	■ No change
matrix.js	143.66 KB	143.66 KB	■ No change
odspClient.js	519.75 KB	519.75 KB	■ No change
odspDriver.js	97.3 KB	97.3 KB	■ No change
odspPrefetchSnapshot.js	42.16 KB	42.16 KB	■ No change
sharedString.js	160.18 KB	160.18 KB	■ No change
sharedTree.js	356.74 KB	356.85 KB	⯅ +113 Bytes
Total Size	3.19 MB	3.19 MB	⯅ +226 Bytes

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Baseline commit: 0016b60

Generated by 🚫 dangerJS against 49ee4a7