Feature request: allow sessions table to be exported via batch exports

[abigailbramble]

Feature request

Users would like the ability to export the session table via batch exports.

Additional context

https://posthoghelp.zendesk.com/agent/tickets/18989
https://posthog.com/questions/how-do-you-export-sessions-table

Debug info

No response

[Stockotaco]

+1 on this

[simfish85]

+2 from two separate high paying customers

[timgl]

@simfish85 do you mind adding links to internal slack messages or tickets for future reference?

[simfish85]

https://posthog.slack.com/archives/C06R7TKD508/p1721850055565609
https://posthog.slack.com/archives/C06UTAJJEHM/p1735950533513069

[tomasfarias]

Hello all!

Development of the sessions batch export has finished (#27796). We are testing the model internally and we are inviting any users who wish to export sessions data into the test too. If you wish to start exporting sessions data now, please send us a support request in PostHog. Otherwise, the model will be generally available after the testing finishes.