rather than using the `normalise_phone_number` function, use the
`validate_and_format_phone_number` function - this will also convert
all numbers to international format, which means we won't need to
worry about whether the user enters internaional or UK phone numbers
when searching
the DateRecieved field from MMG comes in with +s instead of spaces,
and uriencoded (the same as how they format their messages)
Make sure we decode this, and then convert to a UTC timestamp
There are three authentication methods:
- requires_no_auth - public endpoint that does not require an Authorisation header
- requires_auth - public endpoints that need an API key in the Authorisation header
- requires_admin_auth - private endpoint that requires an Authorisation header which contains the API key for the defined as the client admin user
