Persist data in Python plugins per query

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

Is it possible to persist data in a Python plugin class?

**Describe the solution you'd like**

I have created a Python plugin for FlowLauncher using `flox`. This plugin has expensive function that takes seconds to complete, and ideally I would like for this function to be executed once (at startup) and never again. This is due to the plugin re-running this function on every `query` function call, which causes users having to wait each time they type something. I have been trying to re-structure the code, to avoid the function being run every time, but haven't managed it. So I'm thinking, am I doing something wrong or is this the default behaviour of how FlowLauncher works? If so, is this something the FlowLauncher team/contributors are planning to solve or is there a workaround?

**Describe alternatives you've considered**

Continue calling the expensive function on every query, although it will require users to wait 1-3 seconds every time they type.

**Additional context**

In case necessary, the plugin I'm referring to is linked [here](https://github.com/marcelmiro/Flow.Launcher.Plugin.AudioEnvironments/blob/main/plugin/audio_environments.py#L81), and the expensive function is called `list_devices`. I also tried to solve this by using `flowlauncher`.

This is my first PR so please let me know if this is not the conventional way of requesting a feature or asking to know if I'm doing something wrong.