fix(next): pass a corrent content-type header in getFile route

[r1tsuu]

Description

Installed mime-types to @payloadcms/next
Fixes beta-#88

• I have read and understand the CONTRIBUTING.md document in this repository.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• Existing test suite passes locally with my changes

[r1tsuu]

sorry i pulled from wrong remote

[r1tsuu]

I honestly don't know why payload/package.json and payload/src/utllities/isEntityHidden.ts were changed but i resolved it.

[r1tsuu]

Even though it seems like has something to my PR i don't think it could break opening doc drawer..
i will check locally
upd: actually yes, getFileType.fromFile can return undefined for some reason.

[r1tsuu]

because of importing from payload/node console shows this.

next js doesn't like to import prettier it seems.
and about failing test with the drawer, it opens in the pnpm dev uploads (i did the same like in test, opened the first doc from audio collection, removed file and tried to upload a new), but in e2e it doesn't, i don't have idea
upd: locally this test has passed

[r1tsuu]

#5846 https://github.com/payloadcms/payload/actions/runs/8680804563/job/23802183251?pr=5846
I also got the same failed test within uploads in my other PR not related to this

[JarrodMFlesch]

@r1tsuu I moved file-type to be a peer dep of @payloadcms/next to resolve the webpack error. The upload error is not specific to this PR so no worries there.