Implement OGC API - Processes, Requirement 25, for jobControlOptions async-execute only, and no user preference (Issue #2231)

[francescoingv]

Overview

Added logic to treat process where jobControlOption allow async-execute only.

Related Issue / discussion

Issue #2231

Dependency policy (RFC2)

• [ X ] I have ensured that this PR meets RFC2 requirements

Updates to public demo

• [ X ] I have ensured that breaking changes to the pygeoapi master demo server have been addressed
  • [ X ] 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)

• [ X ] 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
• [ X ] I have already previously agreed to the pygeoapi Contributions and Licensing Guidelines