[PoC] Inspector for editable tree

[sharptrip]

This PR contains the PoC implementation of the "property inspector" based on the new tree DDS and its EditableTree API.

The new inspector utilises the EditableTree API in a "full blown" manner operating with fields and nodes in a generic way when reading. A complete traverse of the tree could be "unchained" starting debugging from here:

FluidFramework/experimental/PropertyDDS/examples/property-inspector/src/newInspector.tsx

Line 301 in 3468817

return forEachNode(nodeToRows, rowData, [], "", addNewDataLine);

In contrast, the code also uses a not yet published "contextually typed API" and "simple assignments", which allows users to change data in a more convenient way:

FluidFramework/experimental/PropertyDDS/examples/property-inspector/src/newInspector.tsx

Lines 138 to 149 in 3468817

	const value = defaultPrimitiveValues[typeid];
	if (isUnwrappedNode(rowData.parent)) {
	(rowData.parent as ContextuallyTypedNodeDataObject)[brand<FieldKey>(name)] = {
	[typeNameSymbol]: brand(typeid),
	[valueSymbol]: value,
	};
	} else {
	(rowData.parent as MarkedArrayLike<ContextuallyTypedNodeData>)[Number(name)] = {
	[typeNameSymbol]: brand(typeid),
	[valueSymbol]: value,
	};
	}

You can check the tests in the corresponding PR to get an idea of what it's all about: microsoft#13292

!Attention!

This EditableTree API change is not yet available (not even as a PR).

[sharptrip]

New version with transaction handling #22