fix: memory leak in task problem monitor

[SimonSiefke]

Fixes a memory leak in task problem monitor.

Overview

It seems a problem matcher can be added to a terminal again, e.g. when re-running a task, this function would be called again with the same terminal since terminals are reused between tasks

addTerminal(terminal: ITerminalInstance, problemMatcher: AbstractProblemCollector) {
	this.terminalMarkerMap.set(terminal.instanceId, {
		resources: new Map<string, URI>(),
		markers: new Map<string, Map<string, IMarkerData>>()
	});

	const store = new DisposableStore();
	this.terminalDisposables.set(terminal.instanceId, store); 

This line this.terminalDisposables.set(terminal.instanceId, store) registers the store for the terminal, but doesn't dispose the previous registered store if there is one.

Change

The change is to use a DisposableMap which ensures the already registered disposable gets disposed if there is one.

Before

When running a task 97 times, the number of functions grows by each time in several places, one of which is task problem monitor.

{
  "namedFunctionCount3": [
	/* some more data omitted */
  {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/workbench.desktop.main.js:3019:8513",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/taskTerminalStatus.ts:75:65",
      "originalName": "TaskTerminalStatus.addTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/workbench.desktop.main.js:3019:11261",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/taskProblemMonitor.ts:35:32",
      "originalName": "TaskProblemMonitor.addTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/workbench.desktop.main.js:3021:11006",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts:1051:60",
      "originalName": "TerminalTaskSystem._executeInTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/workbench.desktop.main.js:3019:11385",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/taskProblemMonitor.ts:41:44",
      "originalName": "TaskProblemMonitor.addTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/workbench.desktop.main.js:3019:11732",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/taskProblemMonitor.ts:64:60",
      "originalName": "TaskProblemMonitor.addTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/workbench.desktop.main.js:3021:11503",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts:1073:39",
      "originalName": "TerminalTaskSystem._executeInTerminal"
    }
  ],
  "isLeak": true
}

After

Still various possible memory leaks are detected. But not in taskProblemMonitor anymore.

{
  "namedFunctionCount3": [
	/* some more data omitted */
  {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/contrib/tasks/browser/taskTerminalStatus.js:66:50",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/taskTerminalStatus.ts:70:48",
      "originalName": "TaskTerminalStatus.addTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/contrib/tasks/browser/taskTerminalStatus.js:60:54",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/taskTerminalStatus.ts:64:52",
      "originalName": "TaskTerminalStatus.addTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/contrib/tasks/browser/terminalTaskSystem.js:862:41",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts:1074:39",
      "originalName": "TerminalTaskSystem._executeInTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/contrib/tasks/browser/terminalTaskSystem.js:842:62",
      "originalLocation": "src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts:1052:60",
      "originalName": "TerminalTaskSystem._executeInTerminal"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/contrib/terminal/browser/terminalProcessManager.js:388:77",
      "originalLocation": "src/vs/workbench/contrib/terminal/browser/terminalProcessManager.ts:465:74",
      "originalName": "TerminalProcessManager._resolveEnvironment"
    },
    {
      "count": 99,
      "delta": 97,
      "name": "anonymous",
      "sourceLocation": "out/vs/workbench/contrib/terminal/browser/xterm/decorationAddon.js:321:57",
      "originalLocation": "src/vs/workbench/contrib/terminal/browser/xterm/decorationAddon.ts:362:55",
      "originalName": "DecorationAddon._createHover"
    }
  ],
  "isLeak": true
}