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