Support jSpecify @NullMarked and @NullUnmarked

[gaeljw]

In addition to the already supported (or ongoing development) for @NonNull and @Nullable:

• add jspecify NonNull annotation to NotNullAnnots list #24487
• Consider nullable annotations in explicit nulls #21629 and Consider nullable annotations in explicit nulls #21953

It would be nice to have support for @NullMarked and @NullUnmarked. These 2 annotations can be set on a module/package/class and respectively mean that all items in the scope can be considered @NonNull/@Nullable unless explicitly flagged as the opposite.

• jSpecify spec
• Discussion in Contributors forums