Add browser extension support

[bgins]

Summary

This PR fixes/implements the following features

• Adds browser extension support
  • Add config.debugging.emitWindowPostMessages flag to gate window post messages intended for the extension
• Move events to program.on and namespace them with string prefixes
• Adds session event listeners
• Rename window.__webnative to window.__odd

Browser extension support

This PR adds support for connecting and sending messages to the Webnative devtools extension. Messages are sent as window post messages when Webnative debug mode is set to true. Messages are tagged with the browser extension ID or as odd-devtools-ready-message to inform the extension that Webnative is ready to connect.

Window post messages can be completely disabled by setting config.debugging.emitWindowPostMessages to false.

Move events onto program

This PR moves events onto the top-level program and renames them. For example:

program.fileSystem.on("local-change", ({ path, root }) => { ... })

program.on("fileSystem:local-change", ({ path, root }) => { ... })

Session events

Two new events have been added:

export type Session<S> = {
  "session:create": { session: S }
  "session:destroy": { username: string }
}

These events are emitted when a session is created or destroyed. The S generic is filled in with a Session in the implementation.

Let the renaming begin

This PR accounts for renaming Webnative to ODD at points of interaction with the extension, but does not rename everything in the code base.

Test plan (required)

Install the extension locally as described in the Webnative devtools extension repo. Use the release-prep branch.

Run an app with Webnative debug mode set to true. Open the devtools and find the Webnative panel. The panel should show Webnative connected if the extension has successfully connected with Webnative.

See the Test Plan in this PR for a rundown of the functionality provided by the extension: oddsdk/odd-devtools#21.

Check that event emitters are properly exposed at program.on.

Closing issues

Closes #460

After Merge

• Does this change invalidate any docs or tutorials? Yes, the guide will need some updates
• Does this change require a release to be made? We will hold off on release until we have renamed everything internally to ODD and are ready to publish under the new name to npm

[avivash]

Looks awesome, this is going to be so useful for devs! 🚀

[icidasset]

Some concerns and nitpicks, but overall looking great!
Yay for a great dev experience! 🎉 Next step: