Add optional display_name tag

[mrafi97]

What does this PR do?

Add a new tag to each windows_service service check that includes the Windows Service Display Name as the tag display_name.
Add a collect_display_name_as_tag option to control presence/absence of the tag.

Motivation

Customer Requests: https://datadoghq.atlassian.net/browse/WINA-795

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Changelog entries must be created for modifications to shipped code
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[iglendd]

English my second language of course but do you think we can restate it a bit differently for clarity, e.g. Windows Service Display name will be automatically formatted according to Datadog's tagging requirements (https://docs.datadoghq.com/getting_started/tagging/#define-tags) as display_name tag value.

[iglendd]

Not sure if it worth to describe auto-formatting rules.

[iglendd]

I was thinking to replace

        if 'ALL' not in services:
            for service in services_unseen:
                # if a name doesn't match anything (wrong name or no permission to access the service), report UNKNOWN
                status = self.UNKNOWN
                startup_type_string = ServiceView.STARTUP_TYPE_UNKNOWN
                display_name = "Not_Found"

                tags = ['windows_service:{}'.format(service)]

                tags.extend(custom_tags)
                if instance.get('windows_service_startup_type_tag', False):
                    tags.append('windows_service_startup_type:{}'.format(startup_type_string))

                if instance.get('collect_display_name_as_tag', False):
                    tags.append('display_name:{}'.format(display_name))

on something like

        if 'ALL' not in services:
            for service in services_unseen:
                # if a name doesn't match anything (wrong name or no permission to access the service), report UNKNOWN
                status = self.UNKNOWN

                tags = ['windows_service:{}'.format(service)]
                tags.extend(custom_tags)
                if instance.get('windows_service_startup_type_tag', False):
                    tags.append('windows_service_startup_type:{}'.format(ServiceView.STARTUP_TYPE_UNKNOWN))

                if instance.get('collect_display_name_as_tag', False):
                    tags.append('display_name:{}'.format(ServiceView.DISPLAY_NAME_UNKNOWN))