Step Functions: support items.length > 0 in Conditions

[sam-goodwin]

We can support a limited subset of list.length comparisons with the intrinsic IsPresent variables:

if (list.length > 0)

{
  "IsPresent: true,
  "Variable": "$.list[0]"
}

if (list.length  === 0)

{
  "IsPresent: false,
  "Variable": "$.list[0]"
}

if (list.length  === 1)

{
  "And": [
    {
      "IsPresent: true,
      "Variable": "$.list[0]"
    },
    {
      "IsPresent: false,
      "Variable": "$.list[1]"
    },
  ]

[sam-goodwin]

See #36 (comment)

[sam-goodwin]

@thantos is this solved by #468

[thantos]

It's not limited, any numeric comparison to length is supported, but yes.