Implement the pruning of container caches (resume directory) when there
is a mismatch between the current revng components' hash and the saved
one. This functionality is activated via `-check-components-version`.
This commit changes the following method names across the codebase:
* `storeToDisk` -> `store`
* `loadFromDisk` -> `load`
This has been done since the storage is no longer bound to the local
storage.
This commit introduces some changes to how the revng pipeline handles
serializing to disk. Specificaly:
* Pipeline globals (specifically model.yml) are better handled if they
are in a subdirectory. They are now saved in the "context"
subdirectory.
* In python:revng.api the pipeline is serialized whenever there is a
non-reproducible change to the state (e.g. binary upload or model
change).
In the case of analyses this is done conservatively by checking that
the diff produced is not empty.
* The logic for computing a step's subdirectory has been moved to the
pipeline runner, consequently if a step is asked to serialize it
will not create any subdirectories.
* Functionality for saving a single step/context has been exposed in
Pipeline C.
* Finally, all path concatenations are now handled by
llvm::sys::path::append, for extra os-agnosticism.
ContainerSet is now the one that has the burden to check that removal of
0 elements is always a success, rather than offloading that check onto
containers.