feat(workflows): Adds more optional fields to workflows

[d0weinberger]

Why this PR?

The dynatrace_automation_workflow resource was missing several fields supported by the Dynatrace Automation API. Users couldn’t configure important workflow properties like deployment state, execution limits, or workflow-level input parameters, forcing them to manage these settings outside of Terraform.

What has changed?

New workflow-level attributes (all Optional, non-breaking):

HCL Attribute	Type	Default	Description
is_deployed	bool	true	Controls whether the workflow is active and billed, or a draft
owner_type	string	-	Enum: USER / GROUP - type of the workflow owner
hourly_execution_limit	int	1000	Cap on executions per hour
input	string (JSON)	-	Workflow-level input parameters available to all tasks
task_defaults	string (JSON)	-	Default settings applied to all tasks
guide	string	-	Markdown guide text for the workflow (max 10,000 chars)
result	string	-	Result identifier for the workflow

How does it do it?

All changes follow established patterns in this provider:

• Added struct fields to Workflow with correct JSON tags.
• Extended Terraform schema in Schema() with appropriate types, defaults, and validation (StringInSlice, ValidateMaxLength, SuppressJSONorEOT).
• Implemented is_deployed using the *bool + GetOkExists pattern (same as existing isPrivate) to avoid TF SDK default/zero-value pitfalls.
• Implemented input and task_defaults using the existing JSON-string pattern (like Task.Input): map[string]any in Go/API, jsonencode() in HCL.
• Updated MarshalJSON to include all new fields in the custom serialization struct (which injects schemaVersion).
• Updated MarshalHCL / UnmarshalHCL to encode/decode the new fields.

How is it tested?

I added a new Terraform file for E2E testing using the newly introduced fields.

How does it affect users?

• No breaking changes — all new fields are Optional and defaults align with API behavior; existing configurations keep working.
• No state migration needed — additive Optional fields don’t require schema version bumps.
• Users can now manage workflow deployment state, execution limits, input parameters, task defaults, and guides entirely through Terraform.

Issue: CA-18196

[Kirdock]

We agreed not to validate field lengths, since the API might change, right?
Could you remove it?

[Kirdock]

What's the reason for the DiffSupressFunc here? Is there a different behavior (sent data vs received data)?

[Kirdock]

Do we really want to keep this huge markdown?
I don't see a real benefit in having it, and it would just reduce the readability and also maintainability of the example files. For testing, a short string would be enough

[Kirdock]

Really nit, but is new_fields a good pick for a name? If new properties come in, will there be a new-fields2.tf? 😅

[Kirdock]

So, the value on the API side can still be undefined, even if it has a default value?
When running locally, without is_deployed, the value is always defined for me

[Kirdock]

Because of Default: true, the is_deployed should always be set, right?

Here I haven't set the is_deployed