Auto merge of #107141 - notriddle:notriddle/max-lev-distance-2023, r=GuillaumeGomez

rustdoc: compute maximum Levenshtein distance based on the query

Preview: https://notriddle.com/notriddle-rustdoc-demos/search-lev-distance-2023/std/index.html?search=regex

The heuristic is pretty close to the name resolver, maxLevDistance = `Math.floor(queryLen / 3)`.

Fixes #103357
Fixes #82131

Similar to #103710, but following the suggestion in #103710 (comment) to use `floor` instead of `ceil`, and unblocked now that #105796 made it so that setting the max lev distance to `0` doesn't cause substring matches to be removed.

Author: bors