overrideForAll method
Makes moor_ffi use the OpenLibrary function for all Dart platforms.
If this method has been called, it takes precedence over overrideFor.
This method must be called before opening any database.
When using the asynchronous API over isolates, open must be a top-
level function or a static method.
Implementation
void overrideForAll(OpenLibrary open) {
_overriddenForAll = open;
}