Add a rotating list of tips to the inserter help panel

[youknowriad]

This PR updates the inserter help panel to show a different tip on each render (mount).
This is a static list of tips but we could potentially make it extensible in the future.

Testing instructions

• Open the inserter
• Notice that the tip changes each time you open/close the inserter.

[michelleweber]

I'm assuming the copy is what's here?

For the media files, I'd say "automatically insert" rather than "quickly."

For "transform blocks," I think the update doesn't include enough information, because the word "transform" begs the questions "into what?" Suggestion: "Change a block's type by pressing the block icon on the toolbar."

[mtias]

Thanks @michelleweber for the suggestions!

[youknowriad]

Applied the suggestions above, thanks.

[youknowriad]

Should we land this first batch of tips?