Notebook: Missing command palette commands

[kieferrm]

• new cell
• delete cell
• move cell up/down
• run cell
• switch rendered mime type for cell

[rebornix]

This can be done be adding f1 to each action definition but we need to make sure that they all work fine when invoked from command palette.

[roblourens]

Did this for all except changing the output type, this isn't an action and should be refactored.

[roblourens]

Actually I don't think we can really do it for that because there are multiple outputs with different types and there is no concept of a "current output", so you just have to click the one you want to change.