Allow bots to use /channels/:id/store-listing endpoint

[advaith1]

Currently, bots can't access the store-listing endpoint, which returns information for Store channels. I can't think of any reason why bots are blocked from this endpoint, and currently, bots can't access any information about the channel, other than the standard channel settings.

[cakedan]

Weird that they closed this endpoint off since it was open to bots a couple months ago..

[apacheli]

On a side note, there is /store/published-listings/skus/:sku_id which is completely accessible by bots. You won't have any channel context though.

[msciotti]

We don't have plans to open more API functionality around the game store/store channels at this time.