Support upgrading splunk forwarding and accepting ToS

[treydock]

Pull Request (PR) description

Based on Splunk docs (https://docs.splunk.com/Documentation/SplunkCloud/8.0.0/User/UpgradeyourForwarders) the way to upgrade forwarders is manually or with a script and that script essentially stops and then starts splunk with --accept-license --assume-yes. This tries to mimic that behavior. The Exec should only be triggered if the forwarder is already installed.

Output from running this on my test and dev systems:

Notice: /Stage[main]/Splunk::Forwarder::Install/Package[splunkforwarder]/ensure: ensure changed '7.3.2-c60db69f8e32' to '0:7.3.3-7af3758d0d5e' (corrective)
Info: /Stage[main]/Splunk::Forwarder::Install/Package[splunkforwarder]: Scheduling refresh of Exec[splunk-forwarder-accept-tos]
Notice: /Stage[main]/Splunk::Forwarder::Service::Nix/Exec[splunk-forwarder-accept-tos]: Triggered 'refresh' from 1 event
Notice: /Stage[main]/Splunk::Forwarder::Service/Service[SplunkForwarder]/ensure: ensure changed 'stopped' to 'running' (corrective)
Info: /Stage[main]/Splunk::Forwarder::Service/Service[SplunkForwarder]: Unscheduling refresh on Service[SplunkForwarder]

The alternative to this PR is a Bolt task that handles the upgrade but the problem there is would get complicated to support all the ways Splunk forwarders can be installed (local RPM, local yum repo, etc).

[ghoneycutt]

Suggest adding Style/TrailingCommaInArguments to the list of rubocops to ignore.

[treydock]

Fixed rubocop issues

[bastelfreak]

thanks for the PR @treydock !