Undefined database methods - fetch(), etc - commented out in the interface

[herbdool]

Description of the bug

There are a bunch of undefined database methods in my IDE: fetch(), fetchObject(), fetchAll(), fetchMode() which were commented out in https://www.drupal.org/node/331213 when they created DatabaseStatementInterface.

In the class description:

• Some methods in that class are purposefully commented out. Due to a change in
• how PHP defines PDOStatement, we can't define a signature for those methods
• that will work the same way between versions older than 5.2.6 and later
• versions. See http://bugs.php.net/bug.php?id=42452 for more details.

So it seems that since the minimum PHP version is far past 5.2 that these can be uncommented.

I also noticed that the method errorInfo() is undefined where it's called in DatabaseStatementPrefetch so we'll need a "pass-through" to the PDO errorInfo method.

[herbdool]

Turns out to be harder than I thought. There are still incompatible method signatures between 7 and 8. Not sure if we can reconcile them.