Design Ideas for how deal with Post Processing Plugins

## Discussion on Plugin Design for Post-Processing and HP Plugin

We need to initiate a discussion regarding the optimal design for managing plugins related to PP or HP plugin. In certain scenarios, it may not be necessary for some properties, such as geometry optimization, to be executed. This is related to **Issue #731**.

For context, I've been considering the **PP plugin** ([link to the plugin](https://github.com/AndresOrtegaGuerrero/aiidalab-qe-pp)),

### Key Points for Discussion:

1. **External Control of Plugins**:
- Should we implement a mechanism for external control of plugins within the main application?

2. **Defining Post-Processing Workflows**:
- Should certain post-processing tasks be handled in an external notebook instead of the main app?
- If so, what features should be included in this external notebook?
- A **search widget** for structures or workflows
- A **settings panel** to configure options
- A section for **compute resources** and **results** to these are needed
### Considerations:
We should evaluate the user experience and functionality requirements for both approaches to determine the most effective design (Or any other). Input from all will be valuable in shaping the final implementation.

@cpignedoli @edan-bainglass @superstar54 @giovannipizzi @mikibonacci