test: add more validation test cases

[Emyrk]

Some of these cases you would expect it to be an error, but the validation passes

[Emyrk]

So you can pass in "a" for a "number" param... interesting.

You can see it for yourself:

data "coder_parameter" "region" {
  name        = "region"
  type        = "number"
  order       = 1
}

$ CODER_PARAMETER_c697d2981bf416569a16cfbcdec1542b5398f3cc77d2b905819aa99c46ecf6f6=nan terraform apply && terraform show 
# data.coder_parameter.region:
data "coder_parameter" "region" {
    description = "Which region would you like to deploy to?"
    ephemeral   = false
    form_type   = "input"
    id          = "2aec6abf-883a-4618-98c6-6e262e2bfd9b"
    mutable     = false
    name        = "region"
    optional    = false
    order       = 1
    styling     = jsonencode({})
    type        = "number"
    value       = "nan"
}