Notebook diff: renderer support

[rebornix]

Current notebook diff editor only compares and presents the changes in text diff editors, we may also want to support renderers in the diff view just like what we did in the native notebook editor.

[rebornix]

The first step is loading the static renderers in the diff view. It will come with following changes:

• Add view models for notebook diff cell
• Move the layout calculation and caching into the view models
• Add container DOM node for renderers
• Load the static renderers

The next step would be supporting multiple outputs in a single cell, which will require absolutely positioning every output and cache the output position with prefix sum.

[rebornix]

In order to share the webview infra we had in the native notebook editor, we want to make backLayerWebview generic enough to support both output rendering in both editors. To archive that, we want to

• Reuse CellOutputViewModel in diff editor
• backLayerWebview would take a generic editor T and CellOutputViewModel as parameters to render an output

Currently I hacked around everything and have builtin renderers in webview

[rebornix]

By making the webview module generic (I mean literally, `), we share the same code for rendering outputs in the webview. The missing part is loading kernel preload scripts but we can look into them at the end. Now we have output webview rendering on both sides

By making the webview module generic (literally, <T>), we now share the same output webview rendering code. With which we can render outputs on both side