feat: allow input source from pipe

[strazzere]

While performing a bit of experimentation, I found it was easier to allow data to flow from other segments of my machine via piping it in, rather than flushing it to disk. This can speed up the process when pre-processing large amounts of data. This allow allowed me to keep disk space low and just utilize a large ram machine.

Description:

Allow stdin an input source. This was helpful for dealing with large datasets and avoiding the disk (and keeping memory to a decent size). This should let other folks leverage the tool a bit easier when piping data from other tools potentially.

My specific instance was processing a rather large file in memory from the web and just piping to trufflehog. This was automated on an aws machine which a small disk but lots of CPU/memory.

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?

[zricethezav]

@strazzere good lookin' PR. Would you mind adding an example command in the README?

[strazzere]

Documentation fix added

[zricethezav]

@strazzere had a discussion internally, wdyt about calling it stdin instead of pipe?

[strazzere]

It doesn't really matter to me, pipe felt better since it strongly infers this isn't inherently just readable data that is being processed. Though that might literally just be how I think of it. I can change it over to stdin.

[rosecodym]

This looks pretty good! Once you've changed all the names over from "pipe" to "stdin" or "Standard Input" we'd be happy to get it in. (Please change them in both the code and the user-facing text.)

[strazzere]

Requested changes should all be done now, cheers.

[rosecodym]

Very cool, thanks!