Implement enforced pagination for all routes that can return data from collections

[james-skelton]

This will prevent the API from maxing out the server's resources by trying to load large amounts of data into memory at once. At present, the maximum limit will be set to 10,000. If this becomes an issue in future, this can be lowered.

• This limit should be set in a configuration file.
• Setting a limit greater than the maximum in an API call should raise an exception.

[james-skelton]

To-do:

• Add a max pagination setting in the configuration file.
• Use this configuration value in routes*

*Use a .get() approach so that a default value is chosen if the configuration doesn't set one.

general.py

• Add pagination to the get_attribute_values route

ppi.py

• Remove the get_paginated_protein_protein_interactions function
• Add pagination to the get_filtered_protein_protein_interactions function

variant.py

• Add pagination to the get_variant_disorder_associations route
• Add pagination to the get_variant_gene_associations route

[james-skelton]

Pagination is now implemented. The only route (that I'm aware of) which could have it implemented and currently does not is the get_node_ids route.