fix(tree2): Fix move within sequence

[alexvy86]

Description

Fixes assertion code path intended to protect against moving nodes between different kinds of sequences, when moving nodes within a sequence (the source and target sequences are the same, and thus the same kind).

Also moves the assert to earlier in the method to fail fast.

Reviewer Guidance

The review process is outlined on this wiki page.

[msfluid-bot]

⯅ @fluid-example/bundle-size-tests: +16 Bytes

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	444.99 KB	444.99 KB	■ No change
connectionState.js	680 Bytes	680 Bytes	■ No change
containerRuntime.js	238.14 KB	238.14 KB	■ No change
loader.js	178.25 KB	178.25 KB	■ No change
map.js	48.06 KB	48.06 KB	■ No change
matrix.js	141.84 KB	141.84 KB	■ No change
odspDriver.js	90.24 KB	90.24 KB	■ No change
odspPrefetchSnapshot.js	41.75 KB	41.75 KB	■ No change
sharedString.js	162.68 KB	162.68 KB	■ No change
sharedTree2.js	265.97 KB	265.98 KB	⯅ +16 Bytes
Total Size	1.72 MB	1.72 MB	⯅ +16 Bytes

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Baseline commit: f7690e3

Generated by 🚫 dangerJS against 1b4d3e0