YieldVault maxRedeem(...) unnecessarily converts shares to assets and back to shares again

Description

maxRedeem(...) enables users to know how many shares they can redeem. In the case of the borrowing vault, it depends on the amount of debt a user has taken, which is taken into account in _computeFreeAssets(...). In the case of the yield vault, maxRedeem(...) is the balance of the user.

Currently, it converts the balance of the user to assets in _computeFreeAssets(...), and then in maxRedeem(...) back to shares again. This is unnecessary and the code could be refactored to handle these 2 situations.

Recommendation

The YieldVault could override maxRedeem(...) and return the balance of the user directly (if not paused).

Status

Addressed here: Fujicracy/fuji-v2#641