This PR is two unrelated things:

1. Fixes [bug] Repository carousel renders home page unusable due to CPU consumption #503 by setting the maximum number of repositories that actually render in the carousel to 15.
2. Introduces a new middleware functions withAuthV2 and withOptionalAuthV2. Some thoughts:

• Today, almost every server action and api route uses withAuth and withOrgMembership.
• There are allot of obtuse things about these functions (e.g., allowAnonymousAccess needs to be explicitly set when the minimum role is GUEST, the api key hash was passed as a param instead of extracting it from the header, etc.)
• We didn't have any unit tests to verify the business logic that (unfortunately) keeps getting more complicated.

withAuthV2 and withOptionalAuthV2 streamlines things in the following ways:

• It's a single middleware for 90% of our actions. The other 10% are 1) APIs that need elevated roles (in which case, withMinimumOrgRole can be used), or 2) APIs that require authentication but not membership (e.g., invite redemption).
• It doesn't take any parameters other than a callback. API keys (if applicable) are grabbed from the request header. This especially makes it easy in API routes.
• Added a ton of UTs

Currently the getRepos action is using this, but planning on refactoring all actions in a followup PR.