Add re-entrancy errors for TreeCheckout

[noencke]

Description

This prevents the user from doing various actions to a SharedTree view while in the middle of an ongoing tree edit. The current behavior for these scenarios is undefined and currently tends to give unpredictable internal error messages to users.

[msfluid-bot]

Code Coverage Summary

↑ packages.dds.tree.src.shared-tree:
Line Coverage Change: 0.06%    Branch Coverage Change: 0.40%

Metric Name	Baseline coverage	PR coverage	Coverage Diff
Branch Coverage	90.88%	91.28%	↑ 0.40%
Line Coverage	97.28%	97.34%	↑ 0.06%

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Baseline commit: 136a519
Baseline build: 307305
Happy Coding!!

Code coverage comparison check passed!!

[msfluid-bot]

⯅ @fluid-example/bundle-size-tests: +2.35 KB

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	465.72 KB	465.75 KB	⯅ +35 Bytes
azureClient.js	563.04 KB	563.09 KB	⯅ +49 Bytes
connectionState.js	724 Bytes	724 Bytes	■ No change
containerRuntime.js	262.34 KB	262.35 KB	⯅ +14 Bytes
fluidFramework.js	427.12 KB	428.19 KB	⯅ +1.07 KB
loader.js	134.18 KB	134.19 KB	⯅ +14 Bytes
map.js	42.71 KB	42.71 KB	⯅ +7 Bytes
matrix.js	149.84 KB	149.85 KB	⯅ +7 Bytes
odspClient.js	528.83 KB	528.88 KB	⯅ +49 Bytes
odspDriver.js	97.88 KB	97.9 KB	⯅ +21 Bytes
odspPrefetchSnapshot.js	42.81 KB	42.83 KB	⯅ +14 Bytes
sharedString.js	165.77 KB	165.78 KB	⯅ +7 Bytes
sharedTree.js	417.58 KB	418.64 KB	⯅ +1.06 KB
Total Size	3.37 MB	3.37 MB	⯅ +2.35 KB

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Baseline commit: b054eb5

Generated by 🚫 dangerJS against fdacc35