feat: form_type and styling metadata arguments added

[Emyrk]

This PR is in support of dynamic parameters. Changes to coder/coder intends to support this experimentally by the end of April. For current versions of coder, these arguments will be ignored.

What is this?

This adds form_type as a field to parameters. By default, legacy behavior is maintained by deducing the default form_type value from the existing inputs.

Why do this?

To support more form type options in the UI. See the truth table here of all the new types:

terraform-provider-coder/provider/formtype.go

Lines 74 to 91 in 2b5ff08

	// formTypeTruthTable is a map of [`type`][`optionCount` > 0] to `form_type`.
	// The first value in the slice is the default value assuming `form_type` is
	// not specified.
	//
	// The boolean key indicates whether the `options` field is specified.
	// | Type | Options | Specified Form Type | form_type | Notes |
	// |-------------------|---------|---------------------|----------------|--------------------------------|
	// | `string` `number` | Y | | `radio` | |
	// | `string` `number` | Y | `dropdown` | `dropdown` | |
	// | `string` `number` | N | | `input` | |
	// | `string` | N | 'textarea' | `textarea` | |
	// | `number` | N | 'slider' | `slider` | min/max validation |
	// | `bool` | Y | | `radio` | |
	// | `bool` | N | | `checkbox` | |
	// | `bool` | N | `switch` | `switch` | |
	// | `list(string)` | Y | | `radio` | |
	// | `list(string)` | N | | `tag-select` | |
	// | `list(string)` | Y | `multi-select` | `multi-select` | Option values will be `string` |

Example new param

data "coder_parameter" "tools" {
  name        = "Tools"
  description = "What tools do you want to install?"
  type        = "list(string)"
  form_type   = "multi-select"
  styling = jsonencode({
    # Arbitrary JSON object to be passed to the frontend
  })
  default = jsonencode(["git", "docker"])

  option {
    value = "Docker"
    name  = "docker"
    icon  = "/icon/docker.svg"
  }
  option {
    value = "Git"
    name  = "git"
    icon  = "/icon/git.svg"
  }
  option {
    value = "Golang"
    name  = "go"
    icon  = "/icon/go.svg"
  }
  option {
    value = "Typescript"
    name  = "ts"
    icon  = "/icon/typescript.svg"
  }
}

Note on docs

I am unable to add more example params to the docs, as they are used in integration tests that seem to use provider versions without this change? I get this error for above:

2025-04-07T18:26:57.1664097Z     examples_test.go:30: Step 1/1 error: Error running pre-apply refresh: exit status 1
2025-04-07T18:26:57.1664830Z         
2025-04-07T18:26:57.1665915Z         Error: default value "[\"git\",\"docker\"]" is not a valid option, values "git, docker" are missing from the option
2025-04-07T18:26:57.1666653Z         
2025-04-07T18:26:57.1667135Z           with data.coder_parameter.tools,
2025-04-07T18:26:57.1668078Z           on terraform_plugin_test.tf line 119, in data "coder_parameter" "tools":
2025-04-07T18:26:57.1668889Z          119: data "coder_parameter" "tools" {

That error is the error you get using this param on the existing terraform provider. Maybe I have to do some skips with past versions. Regardless, I will update the docs when this gets further upstream to a release.

[johnstcn]

For future readers wishing to understand the source of our woes, it might be good to add some relevant links to existing issues.

[Emyrk]

I actually do not know what to link 🤔.

[johnstcn]

Might be good to explicitly document each type + option value for the possible values of ParameterFormType below.

[Emyrk]

I'd rather defer that to the truth table below. I do not want to document it in 2 places.

[johnstcn]

Good spot! 👍