Types for representing compiler diagnostics. Includes a general-purpose representation
of diagnostics with related information which can be converted into miette::Diagnostic to exploit miette's pretty printing of errors.
Unlike miette, lsp_types, and other diagnostic libraries, the error severities match React Compiler's semantics. The intent is that a given diagnostic may be displayed as an error, warning, or not displayed at all depending on the context in which the compiler is being used. For example, an ESLint plugin powered by React Compiler may ignore InvalidSyntax diagnostics, whereas the regular compiler may report them as errors.