Missing WIKI_TITLE in ShadowingFunctionsDetection crashes Slither

[Xenomega]

When using the inheritance-graph detector in Slither it initializes a ShadowingFunctionsDetection detector which lacks a WIKI_TITLE field, as it is more of a helper than a true vulnerability detector.

Possible remediation includes:
-Change this helper to not be a detector at all.
-Allowing the lack of wiki attributes, causing the detector not to be listed (might make detector writing more error-prone).
-Adding another field to mark a detector as internal, and ignoring this check in that case.

I think the final suggestion might be most desirable if we'd like to maintain the integrity of our existing setup.