Remove widget container after plotly widget view gets destroyed

[cpsievert]

Follow up to #169.

Discovered via https://discord.com/channels/1109483223987277844/1115318728301740112/threads/1331842445071220737

Here's a more minimal reprex of the problem. Note that, to see the problem, click 999999, then go back to 123456. An unwanted empty space is above each plot because the .lm-Widget container element from the previous render doesn't get removed.

import plotly.express as px
from shiny import App, reactive, render, ui

from shinywidgets import output_widget, render_widget

app_ui = ui.page_fluid(
    ui.input_radio_buttons(
        id="station_id_rb",
        label=None,
        choices=["123456", "999999", "abcdef", "None"],
        inline=True,
    ),
    ui.output_ui("toggled_controls"),
)

def stock_plot(stock_ticker: str, location: str):
    df = px.data.stocks()
    return px.line(df, x='date', y=stock_ticker, title=f"location: {location}")

def server(input, output, session):

    stock_tickers = ['GOOG', 'AAPL']

    @render.ui
    def toggled_controls():
        location = input.station_id_rb()
        if location is None or location == "None":
            return "location_unknown"
        else:
            return [
                output_widget(f"plot_{s}_{location}") for s in stock_tickers
            ]

    @reactive.effect
    def _():
        location = input.station_id_rb()
        if location is None or location == "None":
            return
        else:
            for s in stock_tickers:
                @output(id=f"plot_{s}_{location}")
                @render_widget
                def _():
                    return stock_plot(s, location)


app = App(app_ui, server)