[OS X] Open external terminal launch/debug with correct Terminal

• VSCode Version: 1.7.2 - 7ba55c5
• OS Verson: macOS Sierra 10.12.1
• C/C++ for VIsual Studio Code Verison: 0.9.2

When debugging/launching your code, VSC doesn't use your external terminal preference set in settings.json. The same issues was opened under vscode repo and in the discussion, we clarified that the launch.json and the expected behavior is related to the specific debugger rather than the vscode itself.

Steps to Reproduce:

1. In your settings.json, set your terminal to a different one. e.g. for OSX, use:

    // Customizes which terminal application to run on OS X.
   "terminal.external.osxExec": "iTerm.app"

2. In launch.json, set an action with "externalConsole": true

3. Start debugging/running your application

Your application will run in the default Terminal.app

Expected behavior:

The last step should respect your preferences

The Node debugger already deprecated the externalConsole replaced with console. I think the C++ debugger should consider the preferences before launching the external console.

Link to OP

Start with the launch.json externalConsole setting and the settings.json terminal.external.osxExec preference described in the issue. Trace how the C++ debugger launches an external console on macOS, then verify that selecting iTerm.app is respected when debugging or running with externalConsole enabled.