src/vs/workbench/contrib/terminal/browser/terminalGroup.ts/TerminalGroup/moveInstance
class TerminalGroup:	moveInstance(instance: ITerminalInstance, index: number): void {
		const sourceIndex = this.terminalInstances.indexOf(instance);
		if (sourceIndex === -1) {
			return;
		}
		this._terminalInstances.splice(sourceIndex, 1);
		this._terminalInstances.splice(index, 0, instance);
		if (this._splitPaneContainer) {
			this._splitPaneContainer.remove(instance);
			this._splitPaneContainer.split(instance, index);
		}
		this._onInstancesChanged.fire();
	}