Added tabindex on install screens

[mauryaratan]

I was wondering why there is no tabindex on install screen forms so I went ahead and added some on setup-config.php and install.php

Would love to hear back from any developer.

[toscho]

tabindex isn’t needed on that page. You can access all fields without any problem in the correct order.

[helen]

It's not there because it doesn't need to be. As seen in other places in core, extraneous usage of tabindex in the past has actually been detrimental to accessibility. If you are seeing specific reasons why accessibility is made better through the usage of tabindex in this situation, feel free to elaborate.