Consistently use regex validation for DOB and NPI

[Benjamin-Lee]

Right now some fields have inconsistent typing. It would be nice if this were consistently applied. For example, there are multiple types of NPI validation in the schema right now:

                  "npi": {
                        "type": "string",
                        "maxLength": 80,
                        "minLength": 2,
                        "description": "The provider's [National Provider Identifier (NPI)](https://www.stedi.com/docs/healthcare/national-provider-identifier). This identifier is required for all healthcare providers who are eligible to receive an NPI. Some non-traditional providers such as transportation services, durable medical equipment (DME) suppliers, or alternative medicine practitioners are not eligible to receive an NPI. If the provider doesn't have an NPI, you can supply either their `taxId` or `ssn`.",
                        "x-meta": {
                            "title": "National Provider Identifier (NPI)"
                        }
                    },

With regex:

                "npi": {
                        "type": "string",
                        "pattern": "^\\d{10}$|^\\d{15}$",
                        "description": "The individual [National Provider Identifier (NPI)](https://www.stedi.com/docs/healthcare/national-provider-identifier) assigned to the provider."
                    },

And no regex:

                    "npi": {
                        "type": "string",
                        "description": "The provider's [National Provider Identifier (NPI)](https://www.stedi.com/docs/healthcare/national-provider-identifier)."
                    },

Same goes for DOB.