Launch task directly into split terminal

Issue Type: Feature Request

The integrated terminal split panes should support launching a task from the command palette into a split terminal panel.

Here is the current workflow

1. Launch a long-running task from command palette by typing ctrl+p -> task first-watcher-task -> enter. (A new terminal window appears, running the task).
2. Click the split terminal button to create a split terminal.
3. In the split terminal, type the arguments for the second task and run it by pressing the enter key in the terminal. Can’t run ctrl+p -> task second-watcher-task -> enter because that would open a whole new terminal section of its own.

Here is the desired workflow

1. Launch a long-running task from command palette by typing ctrl+p -> task some-watcher-task -> enter. (A new terminal window appears, running the task).
2. Launch the second long-running task from comand palette by typing ctrl+p -> task second-watcher-task -> enter. Somehow, this task runs in a second panel of the split terminal, based on some extra command, a task configuration setting, or perhaps by having focus in an already opened split terminal.

VS Code version: Code - Insiders 1.22.0-insider (81335051b2d1460112905c2bce23c205e7cdd231, 2018-04-03T01:09:54.914Z) OS version: Windows_NT x64 6.1.7601

[TwitchBronBron]

One idea is to create a new terminalGroup field.

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "ionic-serve",
            "type": "shell",
            "command": "ionic serve",
            "isBackground": true,
            "terminalGroup": "watchers"
        },
       {
            "label": "dotnet-serve",
            "type": "shell",
            "command": "dotnet watch",
            "isBackground": true,
            "terminalGroup": "watchers"
        }
    ]
}

Here’s how it would flow:

1. Launch task ionic-serve. No consoles are open, so it creates a new console for the task and gives it the name ‘watchers’.
2. Launch task dotnet-serve. There’s already a terminalGroup with the name watchers, so that terminal is split, and the new dotnet-serve task is run in the right part of the split terminal.

[fleps]

This would be awesome!