Splitscreen Tools in core transcription

An Interface component set for different types of Tools connected to a Project via `.tools`.

## Specifications

1. **Narrowest data scope**: This should not require authentication. The event "tpen-project-loaded" indicates that the `TPEN.activeProject` exists and has a `tools` array.
- The likely sources of this event is the project ID in the query string.
3. **Multiple Types**: Tools are parts of the Project that are intended to be used alongside other interfaces. In Transcription, there are a few types.
- *Split panes* - These tools appear to the right of the main interface, squeezing it down horizontally and allowing for a resizable division.
- *Sidebars* - These tools may also pop in to the right, but at a fixed width that is not resizable by the user.
- *Drawers* - This tray slides into the screen, floating over content until dismissed.
- *Dialog* - Interrupts the workflow and overlays the space until dismissed.
5. **Characterizing Legacy Tools**: TPEN 2.8 has a few types of things we should think about...
- iframe tools are split pane tools with a little shim to drop an iframe in from another place.
- page options are sidebars, though perhaps a sidebar with lots of smaller tools within it that may be turned on or off.
- image parsing is either something that occurs in a completely different interface or a large dialog.
- magnify and inspect interactions make sense in a drawer that comes out and then the glass follows the mouse
- tags/hotkeys and peek-zoom things are not tools and belong to some sort of options configuration.
4. **Event Communication**: It will take work and further design to imagine the type of "plug-in" system of tools we want to use. For iframes, we can add some information to the URLs, but cannot extract from them. Other tools may be given access to `TPEN` to fire events and update active objects. For example, a full page image can be clicked on to jump to a line.