Update sosreport to 4.0

Summary of changes:
- Bump sosreport package from 3.6 to 4.0
- Change sosreport ebuild and package.use to use python 3 rather
  than python 2.7
- Reimplement functionality from existing patches, specifically
  - 'journalctl -o export' in Log plugin for cos
  - linux Release plugin for cos
  - kdump plugin support for cos
- Add new patch to allow sosreport to support cos: remote exec arg
- Drop functionality from patches that has since been added to
  upstream sosreport

Testing:
- Passing the sosreport_test validation test,
  see http://sponge2/7ee63f25-20e1-4bde-9f26-96e02a8bd8a8.
- cuskyctl builds submit lakitu

BUG=b/169947404
TEST=see above
RELEASE_NOTE=Updated sosreport to 4.0 from 3.6

Change-Id: I4a7cc6ac0c929614ddd7c201e212927e15093a5c
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/8140
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Reviewed-by: Roy Yang <royyang@google.com>
Reviewed-by: Dexter Rivera <riverade@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
13 files changed