Usability gemrpc updates

Description

This MR aims at providing two options for gemrpc targeting usability:

1. A configurable port (required for the test beam and the multi-GEM block setups)
2. A possibility not to daemonize the gemrpc server (should allow for easier debugging on the CVP13-based setups)

The current behavior is the default one so no change is expected if the options are not used.

Related Issue

How Has This Been Tested?

All features work as expected on the GE1/1 integration setup. The default behavior is consistent with the current behavior.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.