Enhance documentation with NatSpec for increased readability and for autogeneration of related docs

[zerosnacks]

Related: foundry-rs/book#1303

To do:

• Interfaces
• Base.sol
• console.sol
• console2.sol
• safeconsole.sol
• Script.sol
• StdAssertions.sol
• StdChains.sol
• StdCheats.sol
• StdError.sol
• StdInvariant.sol
• StdJson.sol
• StdMath.sol
• StdStorage.sol
• StdStyle.sol
• StdToml.sol
• StdUtils.sol
• Test.sol
• Vm.sol

Goals:

• Document all public facing functions with @notice
• Mark private variables and functions with underscore prefix
• Unify layouts to follow common best practices of grouping storage variables
• Move internal functions up, private functions down
• Should not modify any user facing function or interface

This will make it easier to autogenerate documentation that we can then load into https://book.getfoundry.sh/reference/forge-std/ and keep it up to date