Make Open vSwitch (Ovs) Bridge network support a standalone dracut module

[coiby]

We can make a standalone dracut module out of the commit 224d310 ("Support setting up Open vSwitch (Ovs) Bridge network"). In order for our kdump dracut module tell dracut to include the future ovs dracut module, we need to move the logic of detecting if it's an OVS bdrige to either the check function or mkdumprd.

[coiby]

As reminded by @daveyoung, we may only install necessary files instead of all package files from openvswitch into kdump initramfs.

[daveyoung]

Looks like below files are probably useful, but I suspect there are still files we can strip from the list. @coiby can you add the ovs reviewer to have a look? We only need necessary binaries, setup scripts, config files, the libraries will be added by dracut-install automatically. No need the docs and build related files.

/usr/bin/ovs-appctl
/usr/bin/ovs-dpctl
/usr/bin/ovs-ofctl
/usr/bin/ovs-pki
/usr/bin/ovs-vsctl
/usr/bin/ovsdb-client
/usr/bin/ovsdb-tool
/usr/bin/vtep-ctl
/usr/sbin/ovs-vswitchd
/usr/sbin/ovs-vswitchd.nodpdk
/usr/sbin/ovsdb-server

/etc/openvswitch/*
/run/openvswitch
/etc/sysconfig/openvswitch

/usr/lib/systemd/system/openvswitch.service
/usr/lib/systemd/system/ovs-delete-transient-ports.service
/usr/lib/systemd/system/ovs-vswitchd.service
/usr/lib/systemd/system/ovsdb-server.service
/usr/lib/sysusers.d/openvswitch.conf
/usr/lib/udev/rules.d/91-vfio.rules

/var/lib/openvswitch
/var/lib/openvswitch/pki
/var/log/openvswitch