Missing validation rules on custom required claims

[dabo8008]

Currently, the DefaultJWTClaimsVerifier checks whether a required claim exists or not. However, it does not check if the claim has a proper value.
It would be a nice option if we could also specify some validation rules for claims, such as:

• isBoolean,
• isBoolean().isTrue()
• isString()
• isString().notEmpty()
• isString().matches()
• isNumber()
• isNumer().min().max(),
• etc.