Arch Linux has no osfinger

Description of Issue

So I'm trying to differentiate between CentOS 6, CentOS 7, RHEL 7, and Arch Linux when setting up e.g. package names.

Normally, this'd be a cinch - if issue #51478 wasn't the case. But it is, so cinch it is not. Arch has no osfinger grain, hence my need to use filter_by lists in the first place.

I'd presume osfinger is intended to be a unique identifier across distros/OSes and versions/releases, yes?

So since Arch is rolling release and should always have all packages kept updated:

It is recommended to perform full system upgrades regularly via Pacman#Upgrading packages, to enjoy both the latest bug fixes and security updates, and also to avoid having to deal with too many package upgrades that require manual intervention at once. When requesting support from the community, it will usually be assumed that the system is up to date.

then I propose the following changes:

• osrelease should always be a fixed string for Arch (and other rolling distros, such as Gentoo): latest (or none, etc. - not left blank)
• osfinger for Arch Linux should be ArchLinux, Arch Linux, Arch-Linux, or the like.

Setup

N/A

Steps to Reproduce Issue

N/A

Versions Report

Master:

Salt Version:
           Salt: 2019.2.0
 
Dependency Versions:
           cffi: 1.12.3
       cherrypy: unknown
       dateutil: Not Installed
      docker-py: Not Installed
          gitdb: 2.0.5
      gitpython: 2.1.11
          ioflo: Not Installed
         Jinja2: 2.8.1
        libgit2: Not Installed
        libnacl: Not Installed
       M2Crypto: Not Installed
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.5.6
   mysql-python: Not Installed
      pycparser: 2.19
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 3.6.8 (default, Apr 25 2019, 21:02:35)
   python-gnupg: Not Installed
         PyYAML: 3.12
          PyZMQ: 15.3.0
           RAET: Not Installed
          smmap: 2.0.5
        timelib: Not Installed
        Tornado: 4.4.2
            ZMQ: 4.1.4
 
System Versions:
           dist: centos 7.6.1810 Core
         locale: UTF-8
        machine: x86_64
        release: 3.10.0-957.27.2.el7.x86_64
         system: Linux
        version: CentOS Linux 7.6.1810 Core

Minion:

Salt Version:
           Salt: 2019.2.0
 
Dependency Versions:
           cffi: Not Installed
       cherrypy: Not Installed
       dateutil: Not Installed
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.10.1
        libgit2: Not Installed
        libnacl: Not Installed
       M2Crypto: 0.34.0
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.6.1
   mysql-python: Not Installed
      pycparser: Not Installed
       pycrypto: 3.8.2
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 2.7.16 (default, Mar 11 2019, 18:59:25)
   python-gnupg: Not Installed
         PyYAML: 5.1.2
          PyZMQ: 18.0.2
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 5.1.1
            ZMQ: 4.3.1
 
System Versions:
           dist:   
         locale: UTF-8
        machine: x86_64
        release: 5.2.10-arch1-1-ARCH
         system: Linux
        version: Not Installed

Start with the Arch Linux grain values shown in the issue and compare them with the proposed osrelease and osfinger conventions for CentOS, RHEL, and other rolling distributions. Decide on the identifiers and verify that Arch reports stable, nonblank values; done means the behavior is documented by coverage for the relevant distributions.