Add static OpenAPI document in Dockerfile

[webb-ben]

Overview

Implementation of the OpenAPI document support noted in #1849 and #2188, generating the full OpenAPI document can be troublesome or take an extended period to generate (some pygeoapi instances we have take >50 seconds) which makes horizontal scaling pygeoapi containers slow. The entrypoint should only generate the OpenAPI document if it does not already exist and respect an existing OpenAPI document. This allows for #2188 to also be resolved with a static OpenAPI document that stays in lock step with a configuration document.

Related Issue / discussion

This is a reimplementation of #1850. The goal of the entrypoint script is to handle entry commands, so while I appreciate that @yharby found a workaround, I think it makes sense to use the entrypoint where possible instead of requiring a user to overwrite the behavior of both the entrypoint and command.

Additional information

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