Allow Embedded Engine to be configured with configuration file

[RomanJRW]

Optimize currently uses the EmbeddedBrokerRule, and its constuctor makes things very easy for us to apply our quite simple config as follows:

this.embeddedBrokerRule = new EmbeddedBrokerRule(ZEEBE_CONFIG_PATH);

The most important config for us is the ElasticsearchExporter we use, but we also set the number of partitions (2) too.

If possible, an equivalent for EZE would be very helpful. I understand that this may be currently possible using a parameter map, but this is a bit more awkward for us to use. We would eventually like to use the JUnit 5 extension too, and I don't think this is currently an option with that.

[saig0]

@RomanJRW thanks for sharing. Most of the configuration in Zeebe is related to the distributed system or other parts that EZE (as a pure workflow engine) doesn't have.

Please list all properties that you would like to configure.

[RomanJRW]

I think everything we care about is ES exporter related. The partition count is not part of exporter configuration, but for us it's only important because we import the data by partition, so need to test with multiple configured. See below for the current state of our configuration file for ITs:

---
zeebe:
  broker:
    cluster:
      partitionsCount: 2
    exporters:
      optimize:
        className: io.camunda.zeebe.exporter.ElasticsearchExporter
        args:
          url: "http://localhost:9200"
          bulk:
            delay: 1
            size: 1
          index:
            prefix: zeebe-record
            createTemplate: true
            command: false
            event: true
            rejection: false
            deployment: false
            process: true
            error: false
            incident: false
            job: false
            jobBatch: false
            message: false
            messageSubscription: false
            variable: true
            variableDocument: false
            processInstance: true
            processInstanceCreation: false
            processMessageSubscription: false