Return 200 on the response headers of a successful get tile request

[doublebyte1]

Overview

For a request like this:
http://localhost:5000/collections/lakes/tiles/WorldCRS84Quad/1/1/1?f=mvt

• If the request is successfull, the api should return status ok (200).

Related issue / discussion

#1499

Additional information

https://docs.ogc.org/is/20-057/20-057.html#toc27

Dependency policy (RFC2)

No dependencies are introduced in this PR

• I have ensured that this PR meets RFC2 requirements

Updates to public demo

• I have ensured that breaking changes to the pygeoapi master demo server have been addressed
  • https://github.com/geopython/demo.pygeoapi.io/blob/master/services/pygeoapi_master/local.config.yml

Contributions and licensing

(as per https://github.com/geopython/pygeoapi/blob/master/CONTRIBUTING.md#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to pygeoapi. I confirm that my contributions to pygeoapi will be compatible with the pygeoapi license guidelines at the time of contribution
• I have already previously agreed to the pygeoapi Contributions and Licensing Guidelines