engine/schema: add guest-os support and mappings for XenServer 7.6

[yadvr]

This adds hypervisor capabilities and mappings for XenServer 7.6

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)

[yadvr]

@blueorangutan package

[blueorangutan]

@rhtyd a Jenkins job has been kicked to build packages. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result: ✔centos6 ✔centos7 ✔debian. JID-39

[yadvr]

@blueorangutan test centos7 xenserver-71

[blueorangutan]

@rhtyd a Trillian-Jenkins test job (centos7 mgmt + xenserver-71) has been kicked to run smoke tests

[yadvr]

How I tested: deployed XCP-NG 7.6.0 env, see that host was recognised as XenServer host with version 7.6.0.

Note: with the change and testing it also proves that for XCP-ng no special mappings need to be added, it will simply use the XenServer version mapping if they exist. cc #3087

[blueorangutan]

Trillian test result (tid-35)
Environment: xenserver-71 (x2), Advanced Networking with Mgmt server 7
Total time taken: 32685 seconds
Marvin logs: https://github.com/blueorangutan/acs-prs/releases/download/trillian/pr3427-t35-xenserver-71.zip
Intermittent failure detected: /marvin/tests/smoke/test_deploy_vm_iso.py
Intermittent failure detected: /marvin/tests/smoke/test_scale_vm.py
Smoke tests completed. 70 look OK, 1 have error(s)
Only failed tests results shown below:

Test	Result	Time (s)	Test File
test_01_scale_vm	Failure	20.65	test_scale_vm.py

[yadvr]

Pinging for review @nvazquez @anuragaw @shwstppr @PaulAngus @andrijapanic @borisstoyanov

[anuragaw]

LGTM
(based on code changes and displayed stats/results on PR)

[shwstppr]

LGTM based on code