feat!: settle the open review questions; release 4.7.0

## feat!: settle the open review questions on roles, diffs, SSH and SNMP

- roles: a driver that sets ROLE itself replaces the role it inherits,
  so a Windows driver on OSDriver is "windows", not also "linux".
- os: OSDriver's account listing is get_os_users; NAPALM's get_users has
  another shape and a runtime stub, so hasattr could not tell.
- README: NAPALM's own getters must come from the driver or a mixin
  listed before the first role base; its stubs win the MRO otherwise.
- firewall/DHCP diffs: an empty key, a key given twice, or one more than
  one live entry holds raises ValueError instead of overwriting by guess;
  live entries without a key are never matched.
- ssh_server: only host key algorithms the host has a key for count as
  staying; when the keys cannot be read, the host key list is not
  touched. sshd_config and its copy keep their file mode (GNU and BSD
  stat), 644 only for a new file.
- SNMP: 64-bit ifXTable octets and ifHighSpeed, with the 32-bit counters
  as fallback for agents without ifXTable.
- pyproject: declare typing-extensions, which models.py imports.

BREAKING CHANGE: OSDriver.get_users is now get_os_users; diffs raise
ValueError on keys that cannot name one entry; plan_ssh_hardening
removes no host key algorithm without host_keys.

## fix: tell "could not read" and "does not install" apart in update and VIP readers

- package_updates: the dnf security reader records dnf's exit status and
  raises when it is missing or non-zero, as the apt reader does; a failed
  dnf no longer reads as "no security advisories".
- host_status: an enabled dnf-automatic.timer counts as auto updates only
  with apply_updates = yes (dnf5's automatic.conf wins over dnf4's);
  dnf-automatic-install.timer always does. Unattended-upgrades counts only
  while the program is installed, not from a conffile left behind.
- virtual_ips: a host with systemctl but without systemd as PID 1 reads as
  "did not look" (None), not as "has none". keepalived blocks whose brace
  is on the next line are read.

BREAKING CHANGE: parse_dnf_security expects DNF_SECURITY_COMMAND's
__DNF_RC marker and raises ValueError without it.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "napalm-device-types"
-version = "4.6.0"
+version = "4.7.0"
 description = "Abstract device-type base classes for NAPALM drivers"
 readme = "README.md"
 requires-python = ">=3.10"
@@ -41,6 +41,7 @@ classifiers = [
 ]
 dependencies = [
     "napalm>=4.0",
+    "typing-extensions>=4.0",
 ]
 
 [project.urls]