Updated @envy/browser start commands and README

[kgpax]

What does this PR do

• Adds scripts for starting the web UI (in dev mode and built mode) and the collector web socket
• Updates build step to copy scripts into a bin folder
• Adds a bin section to package.json to run both collector and viewer scripts.
• This allows @envy/browser to be used like this:

# Step 1: install globally
$ yarn add -D @envy/browser

# Step 2: run with npx
$ npx @envy/browser