[Clang-Tidy] Readability Improvements

[Skylion007]

Motivation and Context

• Add readability checks to Clang-Tidy. Starting with some conservative ones like making sure all auto are properly qualified (ie shows if they are const or a reference etc...).
• No redundant_cstr from strings
• Make sure all const methods are marked as such. Seems to be a very common reviewer suggestion.

How Has This Been Tested

• Clang-Tidy and CI

Types of changes

• Docs change / refactoring / dependency upgrade

Checklist

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes.
• All new and existing tests passed.

[eundersander]

LGTM. I wasn't aware of this best practice for auto usage, but it makes sense.

[mosra]

Good stuff. 👍

I'd personally like to avoid auto in some places (i.e., where the type is not immediately clear from the few lines of diff context), but that's unrelated to this change. This is great.

[jturner65]

LGTM