Import `swh_graph_provenance` as `swh-provenance-db-build`

Given that this package's goal is to generate a provenance database using swh-graph, it makes more sense to have it in this repo (swh-provenance) than in swh-graph.

Import done with:

$ cat /tmp/repl.txt 
swh_graph_provenance::==>swh_provenance_db_build::
$ git filter-repo --path tools/provenance/ --path swh/graph/luigi/provenance.py --path swh/graph/tests/luigi/test_provenance.py --path-rename tools/provenance/:db-build/ --path-rename swh/graph/luigi/provenance.py:swh/provenance/luigi.py --path-rename swh/graph/tests/luigi/test_provenance.py:swh/graph/tests/test_luigi.py --source ../swh-graph --force --refs master --replace-text /tmp/repl.txt