move token burn prep into the shares logic

[ethereumdegen]

(NOTE: This update breaks storage slots )

• Moves the stateful mappings for SharesPreparation into the Shares ERC20 token logic itself so that _afterTokenTransfer can be utilized easily in order to reset preparedness when a user transfers any shares token out of their account
• Removes the auto-preparation from the deposit function to prevent griefing attacks

Seeks to fix the issues described in Issues 60 and 61

[ethereumdegen]

Approved by 0xAdri

ok yeah, sorry I didn't completely understand before, got it now. Yes resetting the delay mappings is correct as it allows prevention of such attacks. Yes the current code then will mitigate both the flash loan issue and the resetting other user's delay mapping issue, it looks good to me!