feat: tree index api prototype

[jenn-le]

Description

• TreeIndex is an interface based off of ReadonlyMap that indexes can adhere to
• AnchorTreeIndex indexes anchors nodes on given keys that can be customized per schema
• createSimpleTreeIndex is a public api that allows users to define the schemas and related keyfinders they want to index on, indexing TreeNodes
• createIdentifierIndex creates an index that keys nodes on their identifiers

TODO expand out this description if we want to use this for the API review but maybe it'd be better to just review off the doc?

Reviewer Guidance

The review process is outlined on this wiki page.

[github-actions[bot]]

🔗 No broken links found! ✅

Your attention to detail is admirable.

linkcheck output

> [email protected] ci:check-links /home/runner/work/FluidFramework/FluidFramework/docs
> start-server-and-test "npm run serve -- --no-open" 3000 check-links

1: starting server using command "npm run serve -- --no-open"
and when url "[ 'http://127.0.0.1:3000' ]" is responding with HTTP status code 200
running tests using command "npm run check-links"


> [email protected] serve
> docusaurus serve --no-open

[SUCCESS] Serving "build" directory at: http://localhost:3000/

> [email protected] check-links
> linkcheck http://localhost:3000 --skip-file skipped-urls.txt

Crawling...

Stats:
  170006 links
    1595 destination URLs
    1825 URLs ignored
       0 warnings
       0 errors

[msfluid-bot]

⯅ @fluid-example/bundle-size-tests: +1.08 KB

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	467.08 KB	467.11 KB	⯅ +35 Bytes
azureClient.js	563.85 KB	563.9 KB	⯅ +49 Bytes
connectionState.js	724 Bytes	724 Bytes	■ No change
containerRuntime.js	263.27 KB	263.29 KB	⯅ +14 Bytes
fluidFramework.js	428.71 KB	429.15 KB	⯅ +444 Bytes
loader.js	134.18 KB	134.19 KB	⯅ +14 Bytes
map.js	42.71 KB	42.71 KB	⯅ +7 Bytes
matrix.js	150.15 KB	150.16 KB	⯅ +7 Bytes
odspClient.js	530.45 KB	530.5 KB	⯅ +49 Bytes
odspDriver.js	98.65 KB	98.67 KB	⯅ +21 Bytes
odspPrefetchSnapshot.js	43.04 KB	43.05 KB	⯅ +14 Bytes
sharedString.js	166.23 KB	166.24 KB	⯅ +7 Bytes
sharedTree.js	419.17 KB	419.6 KB	⯅ +437 Bytes
Total Size	3.38 MB	3.38 MB	⯅ +1.08 KB

---

Baseline commit: abde76d8decbaf2cde8aac68b3fa061a0fe75d92

Generated by :no_entry_sign: dangerJS against 081127668e1033b1004e84de585974e04a618a20