Retrieve properties from elasticsearch on get tile request

[doublebyte1]

Overview

This PR adds a body to the get tile request of the mvt-provider, in order to retireve the values for all the fields in that index. This enables tile clients to render styles based on the values of the fields (see image bellow).

Related Issue / discussion

#1645

Additional information

Client rendering before this change:

Client rendering after this change:

Dependency policy (RFC2)

• 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