Add tasks for checking factories files

[wilkinsona]

For META-INF/spring.factories and META-INF/spring/aot.factories, the tasks could check that:

• Each class listed in the values exists in the current project
• Each value lists classes in alphabetical order
• Each nested class in the values uses its binary name (this avoids at runtime an attempt to load a class that doesn't exist before falling back to the binary name)