Add static preloads notebook contribution

[mjbvz]

For #163511

@DonJayamanne Right now I'm forcing all of these static preloads to be loaded as modules that export an activate function. You can then use this to load additional scripts into the webview

If we need to, we can instead explore loading these preloads as non-module scripts. However these would only be evaluated in the global scope. I do not want to support the old school kernel preload API where we injected global variables with context info

[DonJayamanne]

Thanks for this change, I will have a look at this today and get back to you. Should be fine the way it is.
I dont see this changing any existing renderers or kernel scripts.

[DonJayamanne]

Will these scripts have access to the messaging channel, i.e. can the webview scripts send messages back to the exension host?
From what I can tell they can, however I'm not sure how the extension can listen to these messages, as we don't have an identifier to setup a comms channel.

Note: This was never a requirement, just curious about the capabilities.

[DonJayamanne]

Thanks for this change, I will have a look at this today and get back to you. Should be fine the way it is.
I dont see this changing any existing renderers or kernel scripts.

[DonJayamanne]

as modules that export an activate function.

Is the requirement to just expose an activate function without any arguments, or are there some arguments passed into the active function?

[DonJayamanne]

Thanks @mjbvz
I created a simple js file with an actiavte and include the contents of require.js into that, and this works as expected.
I'll whip up the PRs in Jupyter extension next week (my Monday, your sunday) to make use of this API,
with the plan of removing vscodes AMD loader from being exposed in the webviews.

[mjbvz]

Thanks for testing @DonJayamanne!

I'll merge this initial version and we can keep iterating on it next week