Merge #3777 #3784

3777: Add basic task support r=matklad a=Timmmm

This adds basic support for running `cargo build`, `cargo run`, etc.

Fixes #1935

I have tested this and it seems to work. There are two things I'm not sure about:

1. The workspace folder handling seems wrong - just get the first workspace folder? Is this just a TODO item? I don't know if it is right to lift `workspaceFolder` up to `activate()` but I couldn't see another way.
2. If you manually add an entry to `tasks.json` like this:

```
    {
      "type": "cargo",
      "command": "build",
      "problemMatcher": [
        "$rustc"
      ],
      "group": "build"
    }
```

then VSCode somehow magically knows to run `cargo build`. The documentation for `resolveTask` *sounds* like I should have to implement that for it to work:

```
 * Resolves a task that has no [`execution`](#Task.execution) set. Tasks are
 * often created from information found in the `tasks.json`-file. Such tasks miss
 * the information on how to execute them and a task provider must fill in
 * the missing information in the `resolveTask`-method.
```

But then it also says this:

```
* This method will not be
 * called for tasks returned from the above `provideTasks` method since those
 * tasks are always fully resolved. A valid default implementation for the
 * `resolveTask` method is to return `undefined`.
```

Either way, it works without implementing it so the only thing I can think is that it is doing some kind of crazy pattern matching of the tasks returned by `provideTasks()` and the ones found in `tasks.json`.

3784: Ignore createProgress request in tests r=matklad a=matklad

closes #3783



bors r+
🤖

Co-authored-by: Tim <[email protected]>
Co-authored-by: Aleksey Kladov <[email protected]>