ES|QL query builder integration with the DSL module

[miguelgrinberg]

This change adds a small integration of the ES|QL query builder with the DSL's Document class. It consists of two class methods, Document.esql_from() and Document.esql_execute(). Included are docs updates and a new DSL example that uses this new feature.

[github-actions]

🔍 Preview links for changed docs

• docs/reference/dsl_how_to_guides.md
• docs/reference/dsl_tutorials.md
• docs/reference/esql-query-builder.md

[pquentin]

Thanks! LGTM, except the multi_match change.

[github-actions]

The backport to 8.19 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-8.19 8.19
# Navigate to the new working tree
cd .worktrees/backport-8.19
# Create a new branch
git switch --create backport-3048-to-8.19
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 228e66c702f06e2d8b4e33d77131c0f21c6b34d2
# Push it to GitHub
git push --set-upstream origin backport-3048-to-8.19
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.19

Then, create a pull request where the base branch is 8.19 and the compare/head branch is backport-3048-to-8.19.