fix: correct fbc format extraction from fbclid parameter

[najihmld]

The formatted ClickID value must be of the form version.subdomainIndex.creationTime.<fbclid>, where:

• version is always this prefix: fb

• subdomainIndex is which domain the cookie is defined on ('com' = 0, 'example.com' = 1, 'www.example.com' = 2)

• creationTime is the UNIX time since epoch in milliseconds when the _fbc was stored. If you don't save the _fbc cookie, use the timestamp when you first observed or received this fbclid value

• is the value for the fbclid query parameter in the page URL.

Here’s an example of what the resulting fbc parameter value could look like (note that the portion is invalid):

fb.1.1554763741205.AbCdEfGhIjKlMnOpQrStUvWxYz1234567890