Vuu 47 link layout provider and layout manager provider

[vferraro-scottlogic]

Changes

• add functions to load and retrieve temporary layout in LayoutPersistenceManager and useLayoutManager
• delete layout-config code (now replaced by useLayoutManager and LayoutPersistenceManager)
• remove defaultLayout from NewTheme.examples.tsx (will be returned by the LayoutPersistenceManager.getTempLayout() if no temporary layout is found)
• remove warningLayout from shell (will be returned by the LayoutPersistenceManager.getLayout(id) if no layout matching id is found)
• use loadLayoutById in LayoutList to open saved layout

Bonus Feature: Saved Layouts can now be opened:

[heswell]

Overall the code here looks great. I like the whole Provider/LayoutManager structure. I'm not going to micro-review individual lines. There is one important issue that would stop me merging yet.

What we save when we save a layout is not the current layout - we're saving the full JSON representation of all the loaded layouts. Thus when I load a layout from the layout browser, rather than adding that layout as a child of main-tabs, we replace the whole app layout.

Probably need a function to extract the currently selected layout (ie the Tab of main-tabs from which the menu action was activated) and one to add a layout to the existing structure (we have code for both these things in the layout reducer in layout package.

I should be able to wrap the sample-app and sample basket trading app with a LayoutManagerProvider and they should 'just work' . One does and one doesn't. Again, I think its because of exactly what we're saving