STUB -- [Eng] Update validation language for SSN input

[nichole-aquino]

Design ticket (WIP): #389

The error messages aim to describe what went wrong, and where, in plain language. The error UI also is updated to reflect USWDS styles.

Error type: Invalid set of digits in all locations.
Error message: Social Security Number must have a valid set of digits at the beginning (not 9, 666, or 000), a valid set of digits in the middle (not 00), and a valid set of digits at the end (not 0000).

Error type: Invalid set of digits at the beginning.
Error message: Social Security Number must have a valid set of digits at the beginning (not 9, 666, or 000).

Error type: Invalid set of digits in the middle.
Error message: Social Security Number must have a valid set of digits in the middle (not 00).

Error type: Invalid set of digits at the end.
Error message: Social Security Number must have a valid set of digits at the end (not 0000).

Error type: Invalid set of digits in the middle and end.
Error message: Social Security Number must have a valid set of digits in the middle (not 00), and a valid set of digits at the end (not 0000).

Error type: Invalid amount of digits.
Error message: Social Security Number must have exactly 9 digits.

AC
The changes should apply to the following error types:

• Invalid set of digits in all locations.
• Invalid set of digits at the beginning.
• Invalid set of digits in the middle.
• Invalid set of digits at the end.
• Invalid set of digits in the middle and end.
• Invalid amount of digits.