Create a HTML5 console type on top of VNC and WebMKS

[skateman]

First of all, the MKS console is no longer supported so I'm dropping it completely from the codebase. Then to achieve ManageIQ/manageiq-ui-service#1520 we need to have #392 which is implemented by this PR.

The new meta console type (named HTML5) selects the right console type based on the VM's settings. According to @agrare, the operation determining the enablement of VNC is costly, so we're doing it in the background worker. The UI should ask for this new metatype only!

Closes #392
https://bugzilla.redhat.com/show_bug.cgi?id=1532720

[agrare]

@skateman just to make sure I got this, there are vmrc and html5 type consoles, and under html5 we have vnc and webmks?

[skateman]

@agrare yes, and also SPICE, but not for this provider

[agrare]

Thanks @skateman this looks good to me, we might just want to move some of the if vendor == 'vmware' supports feature checks out of core and into this repo

[skateman]

@agrare the lines you didn't like became irrelevant, so there's no need to move the deleted code 😉

@miq-bot add_label enhancement, hammer/no
@miq-bot add_reviewer @agrare

[skateman]

@agrare this is ready for review