Support filtering on non existing field

[JigarJoshi]

Tigris currently supports filtering on field with certain values (including null). This ask is to support filtering of documents with non existing field.

For example for People collection:

[
  {
    "name" : "test1",
    "DL": "123",
  }.
  {
    "name": "test2",
  }
]

I want to query all the people without DL field.