Add play button for all users

[luabud]

Stop experiment for play button and ship it to all users :)

We should hide the button if the code runner extension is enabled. Also, we could use these icons:

https://github.com/microsoft/vscode-icons/blob/master/icons/light/run.svg
https://github.com/microsoft/vscode-icons/blob/master/icons/dark/run.svg

[ericsnowcurrently]

Prescribed Solution

• drop the experiment
  • experiments.json
  • types
  • checkExperiments() in https://github.com/microsoft/vscode-python/blob/master/src/client/terminals/activation.ts
  • package.json, "editor/title" (drop the other icon)
  • icon files under resource directory
• hide icon if code runner extension installed
  • add condition to "when" clause in package.json
  • telemetry if icon disabled
  • set "when" flag for "code runner" extension in https://github.com/microsoft/vscode-python/blob/master/src/client/terminals/activation.ts

[luabud]

Actually these are the exact same icons that are being used by the code runner extension. Let's use this one instead then:
https://github.com/microsoft/vscode-icons/blob/master/icons/dark/start.svg
https://github.com/microsoft/vscode-icons/blob/master/icons/light/start.svg

These are also closer to the icon we A/B tested it. It's basically the same icon but "hollowed" (to conform with the new icons in VS Code)

[ericsnowcurrently]

This seems to be working using the latest insiders. The output panel says that I'm in the experiment, but I cannot tell if I'm in the old experiment or just by default (the new status quo). My local experiments.json certainly reflects "everyone is in the experiment now", so I guess this is okay.