insights: restrict persisted captured values to a max length

Created by: coury-clark

When a code insight is derived from the captured distinct values of the search results, we need to introduce some constraints that the stored values aren't too long.

Proposal: Truncate the captured values to the first 100 characters in the captured string.

How to handle conflicts, two strings that share the first 100 characters?

1. Add them together
2. Drop one for the other