[Azure Search] Introduce 2019-05-06-Preview swagger

[arv100kri]

Introduce a "base" swagger file for the preview API version 2019-05-06-Preview
The swagger is not complete - this PR will allow us to iterate development on the swagger.

Key changes in this PR:

1. Swagger files for Microsoft.Azure.Search.Data and Microsoft.Azure.Search.Service are added for both "track1" and "track2" (hence the duplicates)
2. The swagger files include -
   • All the models in 2019-05-06
   • $select changes introduced via [Azure Search] Add missing $select parameter to List APIs #7371
   • Customer managed encrypted indexes/synonym maps introduced via Adding sdk support for Encryption with customer managed key to the Azure Search specs #5567 - this feature is still in preview

Latest improvements:

MSFT employees can try out our new experience at OpenAPI Hub - one location for using our validation tools and finding your workflow.

Contribution checklist:

• I have reviewed the documentation for the workflow.
• Validation tools were run on swagger spec(s) and have all been fixed in this PR.
• The OpenAPI Hub was used for checking validation status and next steps.

ARM API Review Checklist

• Service team MUST add the "WaitForARMFeedback" label if the management plane API changes fall into one of the below categories.
• adding/removing APIs.
• adding/removing properties.
• adding/removing API-version.
• adding a new service in Azure.

Failure to comply may result in delays for manifest application. Note this does not apply to data plane APIs.

• If you are blocked on ARM review and want to get the PR merged urgently, please get the ARM oncall for reviews (RP Manifest Approvers team under Azure Resource Manager service) from IcM and reach out to them.
  Please follow the link to find more details on API review process.

[openapi-sdkautomation]

In Testing, Please Ignore

[Logs] (Generated from 98d3615, Iteration 5)

No readme.md specification configuration files were found that are associated with the files modified in this pull request.

[azuresdkci]

Can one of the admins verify this patch?

[AutorestCI]

Automation for azure-sdk-for-go

This PR contains more than 3 context, SDK generation is not enabled. Contexts found:

• search/data-plane/Microsoft.Azure.Search.Data
• search/data-plane/Microsoft.Azure.Search.Data/track1
• search/data-plane/Microsoft.Azure.Search.Service/track1
• search/data-plane/Microsoft.Azure.Search.Service

[bleroy]

Just the one branding change.