Feat(StakeVault): allow users to withdraw tokens unrelated to staking

[3esmit]

Commonly happens that users send tokens wrongly to contracts.
UserVault could allow withdraw balances of tokens that were not staked.

[Pranay-Bhilare]

I would like to contribute for this issue too , and here's how I think it can be easily implemented.

1. Function withdraw with parameters => address of the token and amount.
2. Retrieving amount of tokens wrongly sent to contract by tokenAddress.balanceOf(address(this))
3. if amount > retrieved balance, set amount = retreivedBalance.
4. Transfer amount back to user
5. And for preventing stakedToken to be withdrawned using this, a check can be added, and should be reverted if address of token is of stakedToken.