Revert back to plugins that dont require tomls

### Description

Currently, you _must_ have a `.toml` file describing your plugin to run it in angr-management. This is different from how **every** other decompiler loads plugins: just throw a python script in a plugins folder and you are done. Additionally, now all the example plugins we still have in angr-management don't work anymore (they don't have a toml).

It would be much more convenient for many different plugins if we could go back to a single script ecosystem for plugins.

### Alternatives

_No response_

### Additional context

_No response_