[CodeArena] : Gas optimizations fixes

[maximebrugel]

Contains all gas optimizations issues

• Gas Optimizations code-423n4/2022-02-nested-findings#72 (f2fb697)
• Gas Optimizations code-423n4/2022-02-nested-findings#68 (4c752b1)
• Gas Optimizations code-423n4/2022-02-nested-findings#67 (5d75f4c)
• Gas Optimizations code-423n4/2022-02-nested-findings#57 (f72f8e5)
• Gas Optimizations code-423n4/2022-02-nested-findings#56 (250bca4)
• Gas Optimizations code-423n4/2022-02-nested-findings#55 (ca9b7fd)
• Gas Optimizations code-423n4/2022-02-nested-findings#39 (5cebd50)
• Gas Optimizations code-423n4/2022-02-nested-findings#32 (835fb74)
• Gas Optimizations code-423n4/2022-02-nested-findings#8 (51ccc99)
• Gas Optimizations code-423n4/2022-02-nested-findings#5 (2a82425)
• Gas Optimizations code-423n4/2022-02-nested-findings#28 (33ab760)

[adrien-supizet]

⚠️ The logic has changed here. Is that on purpose?
Previous logic was sending tokens to the owner.

[maximebrugel]

The function is onlyOwner, so msg.sender = owner(). It was better to user msg.sender instead of calling the function.

[adrien-supizet]

Is the gas opt worth doing something like this?
From what I read in the documentation, it should be safe to englobe the rest of the function in the unchecked scope but it still makes me a bit uncomfortable while reading the code.

[maximebrugel]

I added the function calls inside the unchecked block because they need to reach the two variables (amountBought and amountFees ), everything declared inside a block is not reachable (unchecked {...} or simply {...}).
However, It will not effect the _transferFeeWithRoyalty and _transferFeeWithRoyalty that will stay checked, it only affect arithmetic operations :

doc