BRIDGE-801 E2E Tests of Swagger Def

# Summary

This adds an E2E for testing the new swagger new endpoint `/payables/rtps'

# Test Plan

* Run All tests
* Run E2E: get Payables RTP list

Test Results

```

E2E: get Payables RTP list

    ✓ with a valid request (39ms)


    1 passing (532ms)


```

BRIDGE-800 Update swagger definition

# Summary

This updates the swagger and end-to-end tests for the existing `/rtps`
paths to move them under `/receivables/rtps` to leave room for future
development of `/payables/rtps` for the counterparty/payer side.

# Test Plan

* Check the server starts ok
* Check the /docs page shows the new paths
* Check we can still carry out the operations from that page
* Check the unit tests all run and pass