Run freeDiameterd with exec

Merge pull request #3 from michaelarnauts/docker-exec

Make sure freeDiameterd is run as PID 1 so it catches SIGTERM signals

This docker image isn't starting freeDiameterd as PID 1. This causes freeDiameter to miss signals since the bash script will receive those. You can see this when you execute docker run tudorh/freediameter, but you can't kill it with CTRL+C.

This change fixes this, and causes the conatiner to be closed correctly when it has to be terminated.

For more information, see https://petermalmgren.com/signal-handling-docker/

On my Ubuntu 22.04 machine with Virtualbox 7.04 the remote access tab is not reachable.

I don't know if the remote access is working with configuration over the terminal. For this I've to search the right steps to configure it via terminal.

There doesn't seem to be an example of adding the root CA certificate.

I've tried using client->setCACert(rootCACertificate) but it says:

error: base operand of '->' has non-pointer type 'TinyGsmClient' {aka 'TinyGsmSim7600::GsmClientSim7600'}
     client->setCACert(rootCACertificate);
           ^~
exit status 1
base operand of '->' has non-pointer type 'TinyGsmClient' {aka 'TinyGsmSim7600::GsmClientSim7600'}