fix: empty datasource results should be empty arrays

[benPearce1]

[sc-92171]

Fixes: #779

environments before:

  + env_output = {
      + environments = null
      + id           = "Environments 2024-09-10 01:49:17.322748 +0000 UTC"
      + ids          = null
      + name         = null
      + partial_name = "broken"
      + skip         = null
      + space_id     = null
      + take         = null
    }

environments after:

  + output     = {
      + environments = []
      + id           = "Environments 2024-09-10 02:43:19.719235 +0000 UTC"
      + ids          = null
      + name         = null
      + partial_name = "broken"
      + skip         = null
      + space_id     = "Spaces-982"
      + take         = null
    }

tag sets before:

  + output     = {
      + id           = "TagSets-2024-09-10 02:33:49.32293 +0000 UTC"
      + ids          = null
      + partial_name = "broken"
      + skip         = null
      + space_id     = null
      + tag_sets     = null
      + take         = null
    }

tag sets after:

  + output     = {
      + id           = "TagSets-2024-09-10 02:37:56.355514 +0000 UTC"
      + ids          = null
      + partial_name = "broken"
      + skip         = null
      + space_id     = null
      + tag_sets     = []
      + take         = null
    }