Add validator for plugin entrys

[superstar54]

QeApp plugin uses the dictionary to collect the items that to be added. For example

# this is the entry point of the plugin
hello_world ={
"outline": Outline,
"setting": Setting,
"workchain": workchain_and_builder,
"result": Result,
}

The workchain

# register the workchain and builder
workchain_and_builder = {
    "workchain": HelloWorldWorkChain,
    "get_builder": get_builder,
    }

It is better to add a validator if the plugin developer passes the wrong keywords and data type. Pydantic could be a solution.