Remove monaco editor & let vscode render HTML & other mime types

[DonJayamanne]

Thanks for this extension, love it Fixes https://github.com/AnWeber/httpbook/issues/27

Please test in VS Code Insiders, an issue was identified in VS Code & fixed (fix will go out in next release of VS Code).

See here https://code.visualstudio.com/api/extension-guides/notebook#rich-output

[AnWeber]

I will merge the pull request, however I am not entirely happy with the result in the current state of vscode. Monaco Editor has solved a few small problems for me.

• Missing search in output (microsoft/vscode#128665, microsoft/vscode#94239)
• no pretty print of output (solvable in extension)
• horizontal scrolling issue (microsoft/vscode#110825)
• broken renderer issue with css
• accessiblity issue with output end
• broken height of output cells (microsoft/vscode#126863, microsoft/vscode#128391)

For this reason, I will temporarily put the Monaco Renderer into its own extension, so that you can continue to use it if needed.