Update fetchLinkSuggestions to sort results by relevancy (WordPress#6…

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* Update fetchLinkSuggestions to sort results by relevancy

- Rename __experimentalFetchLinkSuggestions to fetchLinkSuggestions.
- Rewrite fetchLinkSuggestions in TypeScript.
- Sort results by relevancy using cosine similiarty between term frequency vectors.

* Fix tsc errors

* Update @wordpress/core-data imports

* Make tokenize unicode aware

* Remove unnecessary mutation

* Add tests for all the helper functions

* Simpler scoring function

* Keep experimental for now

Unlinked contributors: scrobbleme.

Co-authored-by: noisysocks <[email protected]>
Co-authored-by: ellatrix <[email protected]>
Co-authored-by: ntsekouras <[email protected]>
Co-authored-by: ramonjd <[email protected]>
Co-authored-by: andrewserong <[email protected]>
Co-authored-by: skorasaurus <[email protected]>