How to migrate remoting hooks

[bajtos]

This is a follow-up for #3718 and #3922.

Write content for docs/site/migration/models/remoting-hooks.md, explain how to migrate LB3 remoting hooks to LB4 interceptors.

• Global hooks, e.g. app.beforeRemote('**', handlerFn)
• Model-level hooks, e.g. app.beforeRemote('User.**', handlerFn)
• Method-level hooks, e.g. User.beforeRemote('create', handlerFn)

Explain how to map properties provided by LB3 remoting context to LB4 concepts
and how to access that data via Dependency Injection.

Acceptance criteria

Migration guide describing manual steps and covering the following topics:

• Global hooks
• Model-level hooks
• Method-level hooks
• How to map LB3 context properties to LB4 concepts

Use (some of) the examples in LB3 doc page Remote hooks to illustrate the migration process on a real code.