Added a ems_id existence check around VM VNC console button visibility

[h-kataria]

calling 'api_version' for VM with ems_id as nil was throwing an error when accessing Archived/Orphaned vmware VM summary screen(Need to set Console type support is set to 'VNC')

https://bugzilla.redhat.com/show_bug.cgi?id=1472973

@dclarizio please review/test

VMware VM with VNC console button

Orphaned VMware VM with no VNC console button

[dclarizio]

@Loicavenel seeing as both archived and orphaned VMs have no EMS and hence can't open a console, do you think we should totally hide this button or present it disabled with a tooltip saying consoles won't work against them?

[Loicavenel]

@dclarizio
So, if the option is never available, we should hide it.. If this is depending of a state we grey out..
So, here hide it.

Question: For Orphan VMs, why EMS is required to open a console, IP is not enough?

[h-kataria]

@Loicavenel we need to find out the api version of a connected EMS to figure out if that's a supported version, which in case does not exist.

[h-kataria]

Discussed with @agrare and found out that it is not possible to open a VNC console for Archived or Orphaned VMs, so i am going to make changes to this PR to Hide the VNC Console button for such VMs.

[miq-bot]

Checked commit h-kataria@489b001 with ruby 2.2.6, rubocop 0.47.1, and haml-lint 0.20.0
4 files checked, 0 offenses detected
Everything looks fine. ⭐

[Loicavenel]

@h-kataria thanks

[h-kataria]

@dclarizio please review

[simaishi]

Fine backport details:

$ git log -1
commit 887d712d1717d7aaed9176521261e10aa01b56e0
Author: Dan Clarizio <[email protected]>
Date:   Mon Jul 24 12:57:50 2017 -0700

    Merge pull request #1723 from h-kataria/fixed_visibility_code_for_vnc_console_button
    
    Added a ems_id existence check around VM VNC console button visibility
    (cherry picked from commit d08a4c9250db5370f3b75f8fef75601b0ee75589)
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1479929