Improve OpenTelemetryCollectorContainer APIs and implementation

[fabiobrz]

We see some issues randomly popping up when starting an OTel collector container, see discussion here

We've been changing things a bit recently in #316 - and we might need to continue that way to make the class more reliable, e.g.: provide APIs that allow configuration to reflect an existing configuration file and keep as isolated as possible to support multiple instances to be started during one test, rather than a singleton instance.