ESQL in-product help update

[abdonpijpelink]

Summary

This PR updates the in-product help for ESQL with the following:

• Added the CASE, CIDR_MATCH, IS_FINITE, IS_INFINITE, IS_NAN, and POW functions
• Added the LIKE and RLIKE operators

Checklist

Delete any items that are not applicable to this PR.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser).co/support/matrix#matrix_browsers)

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 4a09e07

Failed CI Steps

• FTR Configs #51

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
unifiedSearch	290.9KB	295.4KB	+4.6KB

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[stratoula]

Changes LGTM