Endpoint Queries

[haohangyan]

This PR adds the REST API related to getting statements from graph databases based on various constraints
There are four endpoints added:
get_stmts_for_agent_type: Query Retrieves statements on agent type (subject/subject) as well as the agent name in text
get_stmts_for_source: Retrieves statements based on the source type (e.g "reach")
get_stmts_for_rel_type: Retrieves statements based on the statement type(e.g. "Phosphorylation")
get_statements_mix: A comprehensive endpoint that allows combined filtering by agent name, agent type, source type, and statement type.

Todo

In the get_statements_mix function:

• Rename the function to simply get_statements
• agent_name should be agent and be either a tuple, which assumes (namespace, id) is provided, or a string, which assumes a name is provided.
• Add other_agent and other_role as optional parameters for second agent in query.
• Add MeSH filter, this is missing currently.
• Add paper filter, this is also missing currently.

[kkaris]

I think this looks good overall, I only have minor changes that I think you should look at. Otherwise, I have some suggestions that we should discuss if they make sense or not that we don't necessarily have to implement.

[kkaris]

Just minor changes requested, otherwise it's done.

[kkaris]

Updated description with todo list