[analyzer] AWAIT_IN_WRONG_CONTEXT is not triggered in if condition

[asashour]

Future<bool> doSomething() async => true;

void f1() {
  if (await doSomething()) {}
}

void f2() {
  await doSomething();
}

In f1(), the error message is Unexpected text 'await', which denotes that AWAIT_IN_WRONG_CONTEXT is not reported.

In f2() the error message is correct, and there is a fix to add async.

Once this is fixed, the proposed fix for #49114 chould also be enhanced to add async if the method is not already async.

---

Possibly related failing test:

sdk/pkg/analyzer/test/src/diagnostics/await_in_wrong_context_test.dart

Lines 18 to 19 in c202252

	@failingTest
	test_sync() async {

[bwilkerson]

@jensjoha

I believe that we need to have a consistent handling of await. As reported here, there are places where the parser is producing unexpected_token and places where it's allowing/requiring the analyzer to report the issue. It seems most consistent for the parser to always produce an await expression while parsing an expression and for those cases to always be handled by the analyzer. WDYT?