Add alternate name support for the socket

[kfox1111]

fixes: #177
fixes: #176
fixes: #182

[mrsabath]

I tested this PR on Openshift in IBM Cloud. All the services started correctly. OIDC works as expected. LGTM

[kfox1111]

version support removed in another pr. Remove from here as well.

[drewwells]

Is there an image change to address #177? I was expecting to see an environment variable that points to the location of spire-agent config. Something like this will now work?
$ kubectl -n spire-server exec daemonset/spire-agent -- /opt/spire/bin/spire-agent api validate jwt -audience 'us-box-3' -svid '...'

[kfox1111]

The clients don't honor an environment variable unfortunately. Only looking for the socket at the default location.

Something like this should work now:

kubectl -it -n spire-system exec daemonset/spire-agent -- spire-agent api validate jwt -audience 'us-box-3' -svid '...'