Make other source-views first-class

[timholy]

Currently the typed code is the only "first-class" code view; switching optimization state or other manipulations returns you to the typed view. However, in the longer run it might be nicer to make all the views have the same status, switching modes only when you choose the given selector. We might want to suppress certain options that aren't relevant to particular views from the menu.

Given our callsite display, we probably shouldn't do that until we can annotate, e.g., the source code with type information. To be robust it will require something like https://github.com/JuliaLang/julia/issues/31162.