fix(detectors): Fix bug with empty string and keyword in SQL Injection Detector

[roggenkemper]

adds a few additional checks to the sql injection detector:

1. adds a check for an empty string
2. checks if the key is a SQL keyword, now that we are checking if the key is also in the description.
3. checks if the value is 1 character - can cause false positives if it's a single letter or number

[leeandher]

Suggestion for customizing the detection, but since this is a prototype no need to block 👍 my philosophy was to just replace all hard-coded numbers/limits with settings when possible, but if this is unnecessary feel free to ignore

[leeandher]

Is it worth having a minimum match? I could see false positives for queries like "es" as well. You could add it as a detector setting as well and then customers could tweak the detection

e.g.

len(query_value) < self.settings.get("minimum_match_length")

[roggenkemper]

I think that makes sense , will do it in a diff PR!