feat(bakery/Azure): Changes to extract shared-image-gallery image name from logs

[harikumarks]

This PR is for resolving spinnaker/spinnaker#5448.
When using Azure provider if we have a custom packer template which creates shared gallery image , the "Image" output variable still reference the managed image which also gets created as a part of the shared image gallery version. It is possible to create shared image gallery images by adding extension attributes in bake stage json as it is passed on to the packer template as variables. However the rosco azure bake handler only scraps Managed image id which is also created in the due process. But if one were to create shared gallery image, then the idea is that we don't need managed image id reference anymore. So the output could reference the shared image gallery id and this could be in turn used for deploy. This PR is for that.
Samples changes to packer json and extended attributes in bake stage are as below
Packer changes to include shared image gallery

                          "shared_image_gallery": {
				"subscription": "{{user `azure_sig_src_subscription`}}",
				"resource_group": "{{user `azure_sig_src_resource_group`}}",
				"gallery_name": "{{user `azure_sig_src_gallery_name`}}",
				"image_name": "{{user `azure_sig_src_image_name`}}",
				"image_version": "{{user `azure_sig_src_image_version`}}"
			},

			"shared_image_gallery_destination": {
				"resource_group":"{{user `azure_sig_dst_resource_group`}}",
				"gallery_name": "{{user `azure_sig_dst_gallery_name`}}",
				"image_name": "{{user `azure_sig_dst_image_name`}}",
				"image_version": "{{user `azure_sig_dst_image_version`}}",
				"replication_regions": "{{user `azure_sig_replication_regions`}}"
			},

			"managed_image_name": "{{user `azure_sig_dst_image_name`}}-{{user `azure_sig_dst_image_version`}}",
			"managed_image_resource_group_name":"{{user `azure_sig_dst_resource_group`}}",

Bake stage additional attributes could be added to extended attribute as below

     "extendedAttributes": {
          "azure_sig_dst_gallery_name": "${trigger.parameters.azure_sig_dst_gallery_name}",
          "azure_sig_dst_image_name": "${trigger.parameters.azure_sig_dst_image_name}",
          "azure_sig_dst_image_version": "${trigger.parameters.azure_sig_dst_image_version}",
          "azure_sig_dst_resource_group": "${trigger.parameters.azure_sig_dst_resource_group}",
          "azure_sig_dst_packer_resource_group" : "${trigger.parameters.azure_sig_dst_packer_resource_group}",
          "azure_sig_replication_regions": "${trigger.parameters.azure_sig_replication_regions}",
          "azure_sig_src_gallery_name": "${trigger.parameters.azure_sig_src_gallery_name}",
          "azure_sig_src_image_name": "${trigger.parameters.azure_sig_src_image_name}",
          "azure_sig_src_image_version": "${trigger.parameters.azure_sig_src_image_version}",
          "azure_sig_src_resource_group": "${trigger.parameters.azure_sig_src_resource_group}",
          "azure_sig_src_subscription": "${trigger.parameters.azure_sig_src_subscription}",
          "azure_sig_vm_size": "${trigger.parameters.azure_sig_vm_size}"
        },

[spinnakerbot]

The following commits need their title changed:

• 0be04a6: Adding changes to scrape sharedimage gallery name from logs

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[harikumarks]

LGTM

[ajordens]

Talked with @neil-yechenwei offline and this PR has passed their integration tests, will merge.

[EasyAsABC123]

@ajordens @neil-yechenwei thanks!

[EasyAsABC123]

resolves spinnaker/spinnaker#5448