Log formatting with a template literal

[jorenham]

This format option replaces the showLogLevel, showMethodName and separator options, and allows for way more formatting flexibility.

E.g.

const options = {
    isEnabled: true,
    logLevel : isProduction ? 'error' : 'debug',
    stringifyArguments : false,
    showConsoleColors: true,
    format: "${logLevel} at '${methodName}': ${message} (${args.join(', ')})",
};