Th `ɵɵFactoryDef` type will appear in published libraries, via their typings
files, to describe what type dependencies a DI factory has. The parameters
on this type are used by tooling such as the Language Service to understand
the DI dependencies of the class being created by the factory.
This commit moves the type to the `public_definitions.ts` file alongside
the other types that have a similar role, and it renames it to `ɵɵFactoryDeclaration`
to align it with the other declaration types such as `ɵɵDirectiveDeclaration`
and so on.
PR Close#41119