Support custom log formats

[squatto]

I use a custom log format that is the same as the regular log format, just with the addition of the timezone ("UTC", "MDT", etc.) at the end of the timestamp. Because of this, the log viewer doesn't recognize any of my log entries:

It would be nice to be able to customize the log format in a similar way to how we can customize log paths. I'm sure there's more to it than this (e.g. mapping capture groups to the timestamp and severity), but here's a simple example:

    /**
     * Get the log message formats to show in Herds log viewer.
     */
    public function logMessageFormats() {
        return [
            '^\[([\d\-: ]*[ ]?[A-Z]*?)] (?!:)[\s\S]*?\.(.*?(?=:)): ([\s\S]*?(?=(^\[[\d\-: ]*])|\Z)?)$'
        ];
    }