Implement new short URL service

[streamich]

As part of the new URL Service we will refactor and re-implement from scratch our Short URL Service. This ticket tracks its initial implementation.

• Implement short URL client on the server.
  • Make saved object id and slug of the short URL be separate fields.
  • Allow users to use custom slug and automatically generate human-readable slugs (related Human readable dashboard urls #15023)
    • Generate human-readable slug automatically, if not provided by the client.
    • Escape special characters when searching
    • Allow only [a-zA-Z0-9\.\-\_] characters in slug.
    • Do not allow creating short URL with existing slug.
  • Allow querying short URL by either id or slug.
• Remove all usage of MD5 hashing algorithm in the short URL service.
• Create CRUD+ short URL HTTP endpoints.
  • "Create" — POST /api/short_url
  • "Read" — GET /api/short_url/<id>
  • "Read by slug" — GET /api/short_url/_slug/<slug>
  • "Delete" — DELETE /api/short_url/<id>
• Remove old short URL implementation.
• Make the old creation endpoint say: "the old short URL service was removed, use the new one".

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Part of #87304

[elasticmachine]

Pinging @elastic/kibana-app-services (Team:AppServices)