Implement compression of objects before they are saved into the storage
provider. Each container type can specify which algorithm to use
(currently `none` or `zstd`) and the compression level.
Change byte containers from being just a `using` of the relative class
(e.g. `BytesContainer`) to a full fledged subclass. This has the
following benefits:
* The template arguments are now laid out in the container class body,
making it more readable.
* The creation of a new class creates a new symbol, improving
debuggability as now the container classes have their own name rather
than the expanded base class template.
Make the interface required by `SingleOutputPipe` similar to other
piperuns by requiring a constructor, the use of `PipeRunArgument`s and
the implementation of a non-static `run` function.
This commit is the final step in ensuring all the pipes commit what they
should. It also asserts this actually happens, enabling us to easily
catch future problems.
Replace the stub implementation of invalidation with the proper
implementation. A ReadPathCache is added to each global so that it can
keep tracks of what target are associated to which read paths.
Giacomo Vercesi