feat: Frontend support for file_format in S3 batch export

[tomasfarias]

Problem

Adds a dropdown to the UI for users to select an export format. Needs #20979 to be merged first.

Changes

Form now has a "Format" dropdown:

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

Does this work well for both Cloud and self-hosted?

Yes sir.

How did you test this code?

Properly exported parquet to local MinIO:

import pyarrow.parquet as pq

>>> t = pq.read_table("~/Downloads/2024-03-21T00 00 00+00 00-2024-03-22T00 00 00+00 00.parquet")
>>> t
pyarrow.Table
distinct_id: string
inserted_at: timestamp[us, tz=UTC]
uuid: string
event: string
person_id: string
created_at: timestamp[us, tz=UTC]
timestamp: timestamp[us, tz=UTC]
elements_chain: string
properties: string
person_properties: string

[github-actions]

Size Change: 0 B

Total Size: 824 kB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	824 kB

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