EZP-22617: Implemented ISBN Field Type

_Takes over for #798 to move it forward; cleans up commits a bit, rebases it on top of last changes and fixes the tests._

@iosolinf: You may update your branch with what is here if you'd like to continue in the existing PR, you can also do PR against this branch to add additional things, but hopefully this is more or less ready to merge now so hope you fine with the fact that I opened new one with your commits :)

Original description:
## Implemented ISBN Field Type

Ref: https://jira.ez.no/browse/EZP-22617

This is an attempt to implement this field type in eZ Publish 5.x stack. Most of the code is just an adaptation from what is defined in legacy. I've used Country and URL Field Types as example for the new code. 

**validateISBNChecksum** and **validateISBN13Checksum** methods were included in ISBN\Type, perhaps there's a more suitable place for these methods?

My Integration Test denotes some issues, I was not able to find out where to fix / setup the field settings. Most likely the *ISBN - 13* checkbox is not properly defined.

Is it worth to proceed fixing that in this PR or is it easier for everyone if we just drop it and postpone implementing for the time being?