Adds support for ClangTidyCheck::OptionsView to deteremine:
- If an option is found in the configuration.
- If an integer option read from configuration is parsable to an integer.
- Parse and Serialize enum configuration options directly using a mapping from llvm::StringRef to EnumType.
- If an integer or enum option isn't parseable but there is a default value it will issue a warning to stderr that the config value hasn't been used.
- If an enum option isn't parsable it can provide a hint if the value was a typo.
clang-format-diff not found in user's PATH; not linting file.