add bind-for renderer to index

[Algorush]

• add new component to load model by grid coord and name
• change grid to array in state.js
• add html code with bind-for and antity template

Now the initial loading of the scene using grid data works (bind-for). But I haven't yet changed the methods code in state.js to match the new way the scene is loaded. And I think that adding models can be made even easier

[kfarr]

this is a great start! I'll merge for now and here are notes on next steps:

• [ ] - AG there should not exist two keys of the same grid coordinates (right now you can keep adding more of the same cell to the grid)
• [x] - KF Ensure city hall model is updated from gnanasai
• [ ] - AG? if there is a trigger (spawn) event on a grid cell with an existing object already placed, change the item to the currently selected item in that cell; if the currently selected item is the same as that which is already placed in the cell, increase rotation of existing object at those coordinates by 90º
• [x] - KF city hall should always be visible, rendered its own entity in index.html as a child of the anchor
• [ ] - KF? anchor placement state management and user interface