Support for mounting volume mounts to Siddhi instance

[pcnfernando]

Description:
Let's assume, I have a resource file which I need to use with siddhi-io-file source.
At the moment, we cannot mount this file to the Siddhi Runner instance. We would have to create a custom docker image with the resource file already bundled into the docker image.
Even in this case, if we need to update the resource file, we would have to rebuild the docker image.

This usecase is valid for all cases where we need to use resource files.(siddhi-io-file, siddhi-execution-tensorflow, siddhi-gpl-execution-pmml)