We currently do this thing in a bunch of places:
```
$some_value = $request->getStr('viewPolicy');
try {
$editor->apply(...);
} catch (ValidationException $ex) {
$object->setViewPolicy($some_value);
}
id(new AphrontFormPolicyControl())
->setObject($object);
```
This is unintuitive and silly. It should look like this instead:
```
$some_value = $request->getStr('viewPolicy');
...
id(new AphrontFormPolicyControl())
->setObject($object)
->setValue($some_value);
```
That is, behave like other types of controls do. The logic should be:
- If an explicit value is set, use that.
- Otherwise, use the value on the object.
I //think// this actually already works, based on reading `AphrontFormPolicyControl`. We should convert Calendar to work like this, then convert all other applications which use the bad version to work like this.