[BUG] zypperpkg refresh_db does not support skip_verify

Description
When installing a package on OpenSUSE while having an invalid signature on a separate repository, the installation fails despite having skip_verify set True.

Setup
Set up an OpenSUSE installation (I enjoy Tumbleweed). Install a repository with a bad signature; the Microsoft Teams repository is a good one. Create a state that installs a package:

Install btop:
    pkg.installed:
        - pkg: btop
        - skip_verify: True

Run the state with debug output. Note that the repositories are first refreshed, but without the --no-gpg-checks switch:

[DEBUG   ] Calling Zypper: zypper --non-interactive refresh --force

Running that command fails unless --no-gpg-checks is used, which is what skip_verify should tell it to do.

skip_verify should be passed to refresh_db here; then added to the function signature. If present, prepend "--no-gpg-checks" to refresh_opts before the command is called.

I expect this issue to affect anything that uses it, but for completeness, I've tested only with this environment.

• on-prem machine
• VM (Virtualbox, KVM, etc. please specify)
• VM running on a cloud service, please be explicit and add details
• container (Kubernetes, Docker, containerd, etc. please specify)
• or a combination, please be explicit
• jails if it is FreeBSD
• classic packaging
• used bootstrap to install

Expected behavior
If skip_verify is True on an install state, then verification should also be skipped during package refresh.

Start in salt/modules/zypperpkg.py at refresh_db around lines 1405 and 1440, then inspect the install call around line 1610. Confirm how skip_verify reaches the refresh operation and verify that an install with skip_verify=True refreshes repositories using the no-GPG-checks behavior.