Authentication for simulator:manager and manager:middleware connections

[masonlr]

Goal

The following connections aren't authenticated and need to be:

• simulator->manager (for example the HTTP requested currently in the pbs scripts)
• manager->middleware (for example the manager pushing its status to the middleware)

Acceptance criteria

• [x] All endpoints authenticated

Out of scope

Implementation notes

• Need to decide on whether to use temporary access tokens or a permanent shared secret.

[masonlr]

This issue was addressed by https://github.com/alan-turing-institute/simulate/issues/103.