feat(health): add violating file to create better error message for rtp check

[JohnstonLiu]

Description

Recently I had to debug an issue where I accidentally had packer in my plugin.lua file which resulted in Lazy installing packer. This occurred because I was in the middle of a migration. Whenever I used :checkhealth lazy I would get the following error message

ERROR Found paths on the rtp from another plugin manager packer

but with no information about the violating file itself. I think it would be useful for users to have that information so they can diagnose the root of the error properly.

[github-actions[bot]]

This PR is stale because it has been open 30 days with no activity.