Using the built-in OAuth, how can I access the rest of the fetched Installation from a listener?

Description

The built in OAuth is super convenient and great! It fetches the appropriate Installation from my InstallationStore and uses the tokens in that installation to authorize the incoming events. It also puts the relevant User ID and Bot User ID in context so I can access it from middleware and listeners.

But the Installation has so much more in it than just those properties. For example, the installed scopes are stored, an incoming webhook may be stored, etc. If I wanted to access these, I'd currently have to perform installationStore.fetchInstallation() again inside my listener. The framework did that already though, so that's a waste.

This could be solved in probably a few different ways, but I think one of the simplest would just be to add a new (optional) property called installation on AuthorizeResult. The implementation of authorize() that the built-in OAuth library uses would set that property to the whole Installation it got from fetchInstallation(). Any custom authorize() implementations could also set this value. That installation property would then be added to the context, just like botToken, userToken, etc. Then listeners and middleware could use any installation data.

Requirements (place an x in each of the [ ])

• I've read and understood the Contributing guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've searched for any related issues and avoided creating a duplicate issue.

Start by locating the built-in OAuth authorize() implementation, AuthorizeResult, context construction, and InstallationStore usage in the TypeScript codebase. Trace how botToken and userToken reach listeners, then verify that an Installation can follow the same path and that custom authorize() results remain valid. Done means listeners and middleware can access the fetched Installation without fetching it again.