This adds a wrapper class around the inspector protocol for use in
debugger tests. The interface is intended to stay similar to the
currently exposed DebuggerContext.

Right now, we support adding a listener, (partial) handling of the
AfterCompile event, and enabling/disabling the debugger.

BUG=v8:5530

Review-Url: https://codereview.chromium.org/2451153003
Cr-Commit-Position: refs/heads/master@{#40635}