feat: FreeBSD and OpenBSD drivers, read side

FreeBSDDriver (`freebsd`) and OpenBSDDriver (`openbsd`) on a shared
BsdDriver, for the BSD VMs netOrk provisions and BSD hosts added by hand
(NetOrk/netork#798).

- SSH over exec channels (napalm-device-types' run_on_transport): no PTY,
  stdout and stderr apart, real exit codes; run_command()/open_stream()
  are public. Root through `sudo -S` with the password on stdin, or
  `sudo -n` without one.
- Facts: hostname, release and running kernel (freebsd-version / uname),
  hardware from SMBIOS (kenv) or hw.* sysctls, uptime from kern.boottime.
- Interfaces and addresses (ifconfig -a: ether/lladdr, hex netmasks,
  scoped IPv6), routes (netstat -rn, OpenBSD's abbreviated networks
  written out, host/broadcast/loopback entries left out), ARP (FreeBSD's
  sentences, OpenBSD's table), users and groups, processes (lstart read as
  one five-word field), cron jobs (system crontab and the login user's).
- Parsers are pure functions, tested on output recorded from FreeBSD 15.1
  (hand-installed and cloud image) and OpenBSD 7.9 (NetOrk/netork#793),
  with internal addresses replaced by documentation ranges.

.github/workflows/ci.yml

@@ -0,0 +1,48 @@
+name: CI
+
+on:
+  push:
+    branches: ["**"]
+  pull_request:
+    branches: ["**"]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["3.10", "3.11", "3.12"]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+          cache: pip
+
+      - name: Install package with dev extras
+        run: |
+          python -m pip install --upgrade pip
+          # napalm-device-types lives in git.netork.io/NAPALM, not on PyPI: without this
+          # pip looks there, finds an unrelated 0.1.0 and the job dies before any test.
+          python -m pip install "napalm-device-types @ git+https://git.netork.io/NAPALM/napalm-device-types.git"
+          python -m pip install -e ".[dev]"
+
+      - name: Run unit tests
+        run: |
+          python -m pytest -q --tb=short
+
+      - name: Build wheel and sdist
+        run: |
+          python -m pip install build
+          python -m build
+
+      - name: Upload dist artifacts
+        # v4 refuses to run on Gitea ("not currently supported on GHES").
+        uses: actions/upload-artifact@v3
+        with:
+          name: dist-${{ matrix.python-version }}
+          path: dist/*