Add options to make first names and surnames be adjacent

[jzonthemtn]

Add an optional parameter to the FirstName filter that requires a Surname immediately after.

Likewise, add an optional parameter to the Surname filter that requires a FirstName immediately preceding it.

Both options can be set independently, and both should default to false.

When either option is set to true, that filter should only report a span when it is preceded/followed by a span from the other filter.

[jzonthemtn]

There should likely be a related previouslySeen option in FirstName filter that overrides the proposed option if the first name has been previously seen. For example, the combination John Smith as the first name surname, but instances of just John should also be redacted if the previouslySeen option is set.