disable msg logs for offchain use

[jordy25519]

There's some appetite to disable program msg!logs for drift-rs as it pollutes stdout.
will become more annoying as more production services run on drift-rs.

related: drift-labs/drift-rs#72

thinking we can replace msg! with an opt-in feature flag to disable logs at compile time.

#[macro_export]
macro_rules! msg {
    ($msg:expr) => {
       #[cfg(not(feature = "no_log"))]
        $crate::sol_log($msg)
    };
    ($($arg:tt)*) => {
        #[cfg(not(feature = "no_log"))]
        ($crate::sol_log(&format!($($arg)*)));
    }
}