Make panes extendable

[mikedotexe]

Currently (looking at the code from #1 ) I have a handy dandy directory to put "breakout panes" into. Breakout panes are the separate Terminal/iTerm/Command Prompt windows that show a specific subset of information from whatever is highlighted in the main dashboard.

During a recent meeting, I was demonstrating showing the first Message inside the first transaction of the selected block in the dashboard.

The h.d. directory is:
https://github.com/csli-tools/dashboard/tree/1a3aa3490a69cbff544a27385a9f782d0cccc5f2/src/panes/breakout-panes

but I am not doing anything smart. In the spirit of buttoning up the proof of concept, I still have hardcoded values in the JS file that is called when the user runs npm run pane to list the supported breakout panes.

See:

dashboard/new-pane.js

Lines 6 to 8 in 1a3aa34

	const supportedPanes = {
	'msg': 'Shows the Messages for the selected transaction',
	};

This ticket is for writing a smarter version that looks inside a given directory for "pane files" and lists them.
Keep in mind that in the future, we'd like to have a strategy around this tooling that includes storing basic "user preferences" somewhere. The convention that seems to fit would be to add a ~/.csli directory for the overarching suite of tools.

Some day, perhaps soon, we'll be including a path like that… perhaps showing files like ~/.csli/dashboard/users-pane.js or something.

For now this ticket is just being smart in our own folder, with the ability to give it other folders in the future.

Some day things will be brighter.
Ooo child, things are gonna get cslierrr.