Support the audio changes

[blake-mealey]

Context: https://devforum.roblox.com/t/action-needed-upcoming-changes-to-asset-privacy-for-audio/1701697

Audio will no longer cost Robux to upload but will have monthly limits on the number of assets that can be uploaded.

Our current implementation already supports this (any pre-quota audio assets will be uploaded but after the quota is reached, Roblox will reject requests with an error).

However, to better support this for our users, we should request the user's quotas and log a warning to tell the user how many they have left for the current period and when their quota will be reset. We can also fail early without attempting to upload if the user has already reached their quota.

Our docs also need updating since audio is always free now (just not always allowed).

I think this may also accelerate the need for #63 and #135.