Frontend: Lift restrictions on lazy typechecking options.
The `-experimental-skip-all-function-bodies` flag is specified when producing
modules for indexing. These modules are not used for compilation, so it should
be safe to allow `-experimental-lazy-typecheck` and
`-experimental-skip-non-exportable-decls` as well without
`-enable-library-evolution`.
Resolves rdar://128706306
