CLI: add one-stop shop compression "swh graph compress ...."

Implement a pure Python driver for the entire compression toolchain, equivalent
to the former docker script compress_graph.sh, but much more flexible.

In particular it:

• allows to selectively execute specific steps/ranges of the compression pipeline

• requires much less configuration, with a lot of sane defaults (e.g., physical RAM, classpaths, etc.)

• uses the swh-graph*.jar for all java library needs

• supports proper Python logging and timing via the logging module

• cleans up BV graph and tmpdir as last step, freeing up space