Use Plotly.js bundled module instead of CDN link in demo

[thinkh]

Currently, we must add the import Plotly.js via CDN, because it is impossible to use Plotly.js with Snowpack.

Following Snowpacks instructions to Node built-in could not be resolved leads to the error Cannot read property 'document' of undefined (see plotly/angular-plotly.js#75). Also creating a custom build following the instructions for webpack builds did not work.

I guess that this issue can be resolved, once ...

• Plotly.js updates its D3 version (Bumping d3  plotly/plotly.js#424)
• Plotly.js provides an ES6 confrom bundle (see Native ES6 modules vs. the bundle plotly/plotly.js#3518)

[thinkh]

Might be resolved with Plotly 2.0 .

Finally, we are pleased that you can now import Plotly.js using ES6 import.