Absolutely no code actually persisted the data, so all the reading would always fail.

This PR implements completion for the simple cases of async and void in
a local function context. What it misses cases where parsing incorrectly
considers bare modifiers to be local variable declaration statements
rather than local function declaration statements. This is tracked by
bug #14525.

Fixes #8616
Fixes #8617

Pull common FixAll logic into some helper base types that we can use across many of our code style fixes.

Fixes part 2 of #9674 for both the general code style page and the
naming style option page.

This also removes the superfluous "EnforcementLevel" class in the
NamingPreferences namespace that was basically a duplication of
"NotificationOption"/"NotificationOptionViewModel" in the general
CodeStyle namespace.