feat: authenticate to vsphere base template using ssh private key and ssh auth agent.

[supershal]

What problem does this PR solve?:

• Reverts disabling ssh password authentication for all the users and adds deprecation warning
• Enables ssh private key and ssh auth agent based authentication for base templates

Which issue(s) does this PR fix?:

• https://jira.d2iq.com/browse/D2IQ-92865

Special notes for your reviewer:

The warning will be ansible debug statement

 vsphere-clone: TASK [sysprep : Deprecation warning for disabling password authentication] *****
      sphere-clone: ok: [default] => {
vsphere-clone:     "msg": "WARN: SSH password based authentication will be disabled in future releases"
      vsphere-clone: }

Does this PR introduce a user-facing change?:

enable ssh private key and ssh agent based authentication for vsphere image builder 

[github-actions]

File	Coverage
All files	15%	❌
pkg/ansible/runner.go	0%	❌
pkg/app/artifacts.go	0%	❌
pkg/app/build.go	0%	❌
pkg/app/build_azure.go	2%	❌
pkg/app/build_gcp.go	0%	❌
pkg/app/config.go	48%	❌
pkg/app/errors.go	0%	❌
pkg/app/provision.go	0%	❌
pkg/app/root.go	0%	❌
pkg/app/utils.go	7%	❌
pkg/app/validate.go	0%	❌
pkg/appansible/io.go	0%	❌
pkg/appansible/playbook.go	0%	❌
pkg/azure/azure.go	0%	❌
pkg/logging/logger.go	0%	❌
pkg/packer/manifest.go	0%	❌
pkg/packer/packer.go	0%	❌
pkg/stringutil/rand.go	0%	❌
pkg/version/info.go	8%	❌

Minimum allowed coverage is 75%

Generated by 🐒 cobertura-action against 93b60ae

[supershal]

Since we built the new base 7.9 template from scratch again the intermittent shutdown problem is back :(
centos 7.9 build failed because of shutdown:
https://teamcity.mesosphere.io/buildConfiguration/ClosedSource_KonvoyImageBuilder_E2eRhel79ovaOfflineFips/3606599?
centos 7.9 FIPS build passed: https://teamcity.mesosphere.io/buildConfiguration/ClosedSource_KonvoyImageBuilder_Bui/3606612?buildTab=log&focusLine=3377&linesState=430

All RHEL 8.4 OVA build passed.
We will have to replace base template for RHEL 7.9 manually in vsphere.