Improve normalisation/validation mean for String types

/cc @mtuchowski @kamsi

e.g. we'd like to have just upper case result. This case is normalizable, while in dbjs all we have now is pattern which is treated strict way (if string doesn't match it is assumed invalid and cannot be normalized), Still pattern would not be ideal for upper, lower case as it's not possible to easily and accurately describe such rule with regex.

Summarising this is about two things:

• Allow ease configuration of forced case (lower or upper) on string types and string property descriptors
• Alllow custom normalisation for pattern validation, for feasible cases (e.g. entering - betweet NIP numbers), in such case even if input string doesn't match pattern it may be treated as normalisable, then valid.