New type definitions

[delvedor]

This PR introduces type definitions for requests, responses, and the client itself. There are different noticeable changes, almost all of them will cause a breaking change typescript wise:

• The RequestParams export has been removed
• A new types export has been added, containing the full type definition of Elasticsearch endpoints.
• The client type definition has been rewritten from scratch. Now every API accepts a generic only if the specific API needs to have a generic. You can no longer inject a custom definition per endpoint.

The types are not yet complete, there is still a lot of work to do. We are publishing them early to solicit feedback sooner rather than later. If a definition is broken for you and you can't wait for a fix, please use the @ts-expect-error comment. In this way, as soon as the definition is fixed, you will get a compilation error.

There are some APIs (brand new ones) that are not yet covered, those API will have the TODO type, which is an alias to Record<string, any>.

[github-actions]

The backport to 7.x 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-7.x 7.x
# Navigate to the new working tree
cd .worktrees/backport-7.x
# Create a new branch
git switch --create backport-1358-to-7.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick ---mainline 1 f86a79cb26821ed7a748f54a6dbf51cd61471460
# Push it to GitHub
git push --set-upstream origin backport-1358-to-7.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-7.x

Then, create a pull request where the base branch is 7.x and the compare/head branch is backport-1358-to-7.x.