Rewrote getOpenMageVersion() to be faster

[fballiano]

The implode shouldn't be necessary, so I made a try rewriting the method in order to make it easier and a tiny bit faster

[kiatng]

In my test, there is no significant diff. For one thousand iterations:

1. original: ~ 250 microsec
2. new: ~270 microsec; yes, it is worse

I suggest to close this PR.

[fballiano]

this new version doesn't use implode, doesn't use trim, has less variable assignations and from my measurements it's more stable (in terms speed measurements, while when there are functions calling the measurements bounce a bit faster/slower).

[Sdfendor]

I like the cleaner structure and will approve. Just to mention it though, what do you think about a version with a switch instead:

public static function getOpenMageVersion(): string
{
    $info = self::getOpenMageVersionInfo();
    $versionString = "{$info['major']}.{$info['minor']}.{$info['patch']}";

    switch (true) {
        case ($info['stability'] && $info['number']):
            return "{$versionString}-{$info['stability']}.{$info['number']}";
        case ($info['stability']):
            return "{$versionString}-{$info['stability']}";
        case ($info['number']):
            return "{$versionString}-{$info['number']}";
        default:
            return $versionString;
    }
}

Does this improve readibility even further?

An additional benefit for the future (when - hopefully soon - PHP 8 becomes the minimum version) is, that we then can use match and transform the redundant returns into one return in front of the statement.

[fballiano]

mmmmm I kinda don't like the "switch true" :-\\