Enable array for sphinx codes and require randomstring to access the endpoint

[ecurrencyhodler]

Context

Right now I can only upload a connection code one sphinx code at a time. Let's enable the ability to upload several at once using an array and also requiring a random and persistent string in order to access the endpoint.

The other option was to gate access to the endpoint using a token but we felt as if it was overkill. Setting and using a random string would also make it easier to test adding sphinx codes for E2E testing using cypress.

Acceptance Criteria

• I've tested on Chrome
• I've created a test that asserts the endpoint can only be access if the set random string is provided
• I've created a test that asserts that multiple codes can be uploaded using a random string
• I have rebased and tested locally before submitting my PR
• I can submit a pr within 2 days of taking the bounty

Here is an example backend test