Add Aragorn pathfinder

[gloriachin]

Example query:
{
"message": {
"query_graph": {
"nodes": {
"sn": {
"ids": [
"MONDO:0004979"
],
"categories": [
"biolink:Disease"
],
"set_interpretation": "BATCH",
"constraints": [],
"member_ids": []
},
"on": {
"ids": [
"CHEBI:45783"
],
"categories": [
"biolink:Drug"
],
"set_interpretation": "BATCH",
"constraints": [],
"member_ids": []
}
},
"paths": {
"p0": {
"subject": "sn",
"object": "on"
}
}
}
}
}

End point: https://aragorn.test.transltr.io/aragorn/query

[yjzhang]

Docs for the query: https://aragorn.test.transltr.io/aragorn/docs#/ARAGORN/sync_query_handler_query_post