Prefix / Suffix support

This patch was successfully applying to 2.0.0-beta1 but does not apply to 2.0.0-beta2.

Basic reroll of patch #13 for 2.0.0-beta2 does not address test issues in #14.

Patch #16 applied successfully.

This patch adds the prefix and suffix in the field display and they are not saved with the serial number. My use case needs the prefix saved with the field because I want the serial number to be searchable in Search API. What is indexed in Search API is the core serial number without the prefix so anyone searching the full serial number will not find the item.

I finally went with Random Number Field → .

Sure, patch $13 was failing on 2.0.0-beta2 while patch #16 applied successfully.

It's possible to have this patch in 2.0.0-beta3 too?
Thanks.