Add --gdpr-expressions-file option

[beuss]

Similar to replacements-file

[bomoko]

@beuss - this actually gets to one of the reasons these have taken so long to get to - I wasn't entirely sure we wanted to support both the replacements and the expressions, but having your head in this too is useful.
Do you think having both is actually useful?
Maybe this should be an issue we can discuss generally before we pull this in.

[beuss]

I have to admit that I've been surprised when starting to use the tool by the split of the two concepts. IMHO since you use JSON for configuration bits, you can have a single structure with either a "replacement" or an "expression" as attribute.
If you look at eg. beuss@16c91cd I added more options to replacements.
I think there should be only one config file and we determine if it's a replacement or expression for each column by looking at "expression" or "formatter" entry.

[segadora]

Consider splitting the lines like this

            $dumpSettings['gdpr-expressions'] = json_decode(
                file_get_contents($dumpSettings['gdpr-expressions-file']),
                true
            )

It will make it easier to read