Get flow settings api method for JSON-RPC V2 plugins

**Is your feature request related to a problem? Please describe.**

The only way for JSON-RPC plugins to get flow launcher settings is by reading the json files, which doesn't seem like a good UI.

**Describe the solution you'd like**

A `getFlowSettings` method to get all of these settings (like proxy settings, version, etc)

**Describe alternatives you've considered**

Reading the .json file(s) directly

**Additional context**

Start by locating the JSON-RPC V2 plugin API and the existing flow settings source, including the JSON files currently read by plugins. Define the getFlowSettings response around the settings named in the issue, such as proxy settings and version, then verify that a plugin can retrieve them without reading files directly.

Written by the indexing model from the issue text.