[clang-tools-extra] [clang-tidy] Enhance modernize-use-starts-ends-with to handle substr patterns (PR #116033)

[Nicolas van Kempen via cfe-commits]

https://github.com/nicovank commented:

Nice! Few comments. I would like to have a single consolidated strategy to the FixIt generation if possible, I think that would be cleaner and I think it is possible. Some mix of what you added in the `IsSubstr` case and in the other existing cases should work. As mentioned I'll take another look later today or tomorrow morning.

https://github.com/llvm/llvm-project/pull/116033