Need a Flask configuration mechanism to disable rate limiter

[csw]

The rate limiting is hard-coded to e.g. 2 requests/second for the /variantvalidator/ endpoint, which is not suitable for my workload (against an internal instance!). It can be disabled dynamically through Flask's configuration mechanism with Flask-Limiter's RATELIMIT_ENABLED setting, but as far as I can tell, the application doesn't provide a way to set Flask settings without code changes. Enabling Flask's environment variable configuration mechanism will allow the rate limiter to be disabled by simply setting FLASK_RATELIMIT_ENABLED=. This could also be done via a configuration file, but being able to use environment variables as well is more convenient for containerized deployment.

I've tested this out, and I have the necessary change on my flask-env-vars branch. Please let me know if you'd rather approach this differently; I'll be happy to make changes or open a PR.

[Peter-J-Freeman]

Again, if you can PR into develop_3.0.0, it would be grear ro be able to include these changes. Thanks @csw

[Peter-J-Freeman]

We can make changes together on the PR if required :)