Fix issues with revalidateTag/revalidatePath

[conico974]

• Fix revalidateTag for next 15+
• Fix revalidatePath not clearing the fetch cache ( When doing a revalidatePath('/whatever'), all the fetch or unstable_cache inside this route would return the cached value instead of refetching )

There is a few things that we need to think about:
Right now the fetch cache in OpenNext works in a different way than in next start to take full advantage of DynamoDB.
In next start for every get to the incremental cache, they check for every tag used in this get ( and this include layout, page and fetch cache tags ), we only check given the path which entry in DDB is newer, and if so consider the cache entry stale. This mean we can make one single optimized query to DDB instead of either multiple get or an expensive scan/query.
On the other hand the current DDB solution requires a lot more write than the default cache included in next ( They only write on revalidateTag )

I think in the future we should probably support the 2 type of cache ( The next cache could be easily implemented in SQL for example, and it's way better to do it that way in SQL than the DDB way ). Even in DDB, someone barely using on demand revalidation would benefit from a next type of cache.

The other thing is, we may want to allow the revalidatePath to not clear the fetch cache, this gives a lot more flexibility and would allow to invalidate only what's really needed ( But that's not how next works right now ). Not sure if that's something that people may want. We could introduce an env variable that if set would make it work like right now ( it's still possible to clear the fetch cache individually using revalidateTag and some custom tag )

[changeset-bot]

🦋 Changeset detected

Latest commit: 9463e64

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
open-next	Patch
app-pages-router	Patch
app-router	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
open-next	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 19, 2024 8:49am

[sommeeeer]

wow @conico974 did you really just fix this today aswell 👏

you are such an inspiration!

[khuezy]

LGTM!