fix: autocomplete indent on object within an array

[rickcowan]

What does this PR do?

Fixes an issue where the indent is incorrect for an object within an array that is also within an array.

Given the following schema:

{
  "type": "object",
  "properties": {
    "array1": {
      "type": "array",
      "items": {
        "type": "object",
        "required": ["thing1"],
        "properties": {
          "thing1": {
            "type": "object",
            "required": ["array2"],
            "properties": {
              "array2": {
                "type": "array",
                "items": {
                  "type": "object",
                  "required": ["thing2", "type"],
                  "properties": {
                    "type": {
                      "type": "string"
                    },
                    "thing2": {
                      "type": "object",
                      "required": ["item1", "item2"],
                      "properties": {
                        "item1": { "type": "string" },
                        "item2": { "type": "string" }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

When autocomplete is attempted on:

array1:
  - #cursor here

It previously autocompleted to:

array1:
  - thing1:
      array2:
        - type: 
          thing2:
          item1: 
          item2: 

After the fix it correctly indents as:

array1:
  - thing1:
      array2:
        - type: 
          thing2:
            item1: 
            item2: 

The prior code that added indentation should now be handled by this fix: redhat-developer#634

What issues does this PR fix or reference?

https://app.zenhub.com/workspaces/eusa-standup-board---6071eb7d59410e000e9bc963/issues/jigx-com/jigx-builder/307

Is it tested? How?

Manual testing and unit test.

[p-spacek]

not sure why they had 'two spaces' instead of ${this.indentation}... but I think it wasn't correct.

[p-spacek]

two spaces are there because of the standard indentation?
if yes, there should be ${this.indentation} instead
because indentation could be 4 spaces, tabulator, 2 spaces