Add support for the new syntax

Add before hook also
Add support for nested contexts
Passing hooks spec
Passing example_group_spec

I have some doubts with failing and running specs, so I'm going to delay this
decision a bit more
Migrate reporter specs
Migrate pending example group stuff
Implement pending examples features
Extract several predicates for removing duplication
Uncomment examples for reporting pending examples and example groups
Use pending for all pending tests
Migrate settings spec

I still have to implement the subject feature
Implement implicit subject feature
Refactor for removing settings creation

Let mamba do it for you! :metal:
Remove sure dependency and upgrade doublex one
Use a python3 compatible exec
Extract ast manipulation to its own module
Extract methods for managing contexts, examples and hooks
Extract a description_name method
Remove unused context field
Rename methods for avoid duplication