[#297] Refactor the "File not found" error logging messages for absent files when disabling credo checks

[liamstevens111]

Attempts to resolve #297

What happened 👀

Few changes to the file to separate the the check and files depending on the project type. Not the most efficient but an example I thought of although does make it larger. Not sure if it's easier to read or not.

Insight 📝

• Should the wiki page mention not to install dependencies after running mix phx.new awesome_project? Or is this not important anymore? I know it's still mentioned in the Wiki so not sure
• Do we need to include the phoenix dependency in mix.exs for Mix only (non-phoenix) project types? It is added in Project.init_base_module_fields. Or is there no harm in leaving this here for now?

Proof Of Work 📹

Show us the implementation: screenshots, GIFs, etc.