Add proper documentation

[g-bohncke]

The documentation is missing details on all the run arguments, for example:

1. In the code I found that you can pass in -DappFilePath to overrule using the artifactId for searching the .flogo file.

Additionally when you use this flag you need to set a path so:
mvn clean test -DappFilePath=example.flogo will break the test due to https://github.com/TIBCOSoftware/flogo-maven-plugin/blob/main/src/main/java/com/tibco/flogo/maven/mojo/FlogoTestMojo.java#L89 expecting a path
mvn clean test -DappFilePath=./example.flogo will work.

2. it would be nice if the documentation contains useful advices on other easy to use maven arguments such as:
   mvn com.tibco.plugins:flogo-maven-plugin:flogotest -DappFilePath=./example.flogo
   skipping the constant re-building due to the build being hooked to the compile phase and not the package phase. and when your just fixing and re-running test there is no need to rebuild the app every time.

3. I was pointed to this for the question of how to obtain code coverage:
   aperently all this maven plugin does for this is setting yet other undocumented flags:

if (FlogoTestConfig.INSTANCE.getPreserveIO()) {
            launchConfig.add("--test-preserve-io");
        } else {
            launchConfig.add("--collect-coverage");
}

Can this be looked into?