[ANCHOR-544] Fix date fields in SEP-12 PUT /customer

[philipliu]

Description

This changes the id_issue_date and id_expiration_date type to a String instead of an Instant. Validation has been added to these fields to ensure they are in ISO-8601 date-only format before passing it to the business server.

Context

SEP-9 date fields should be in ISO-8601 date-only format.

Testing

• ./gradlew test

Documentation

N/A

Known limitations

N/A

[Ifropc]

Shouldn't we accept ISO 8601 date time too for backward compatibility? Not sure if anybody uses it right not, but simple regex replacement of "T.*", "" could be sufficient

[philipliu]

@Ifropc Good point. I think there is less room for error if we avoid using regex, so I'll parse instead.

[Ifropc]

Ideally we would want to pass ISO-8601 date-only format to business server but I think date-time is acceptable