[feat] Ability to specify group name without modifying id.

[legander]

HAR fragment (page with name property)

// Input
{
  "id": "group_0_id",
  "title": "Title",
  "name": "Name"
}

// Output
group("Name - Title", function () {
  response = http.get("https://test.k6.io/");
});

HAR fragment (page without name property). Still generating same code as before this PR.

// Input
{
  "id": "group_0_id",
  "title": "Title",
}

// Output
group("group_0_id - Title", function () {
  response = http.get("https://test.k6.io/");
});

[EdvinasDaugirdas]

Can we also add a validation rule to be sure that name is always a string? Something similar to this:

https://github.com/k6io/har-to-k6/blob/e7084bd5adfd5ed39f51c1936c598a0ceec94fd0/src/validate/page.js#L50

[EdvinasDaugirdas]

LGTM 🚀