Update dataset kind documentation and track dataset creation even if mapFields failed

[a-khaledf]

Problem

Fixes AXM-10068 AXM-10069

When creating or updating a dataset, if the primary operation succeeded but the subsequent UpdateMapFields call failed, the Terraform state was not updated with the created/updated dataset. This caused:

• Orphaned resources: Datasets created in Axiom but not tracked in Terraform state
• "Already exists" errors: On retry, Terraform would attempt to create the dataset again
• State drift: Users couldn't manage the resource without manual intervention (import, etc.)

Changes

1. Fixed Create function (resource_dataset.go)

• State is now set immediately after successful dataset creation
• UpdateMapFields is performed as a secondary operation
• If UpdateMapFields fails, the dataset is already tracked in state (preventing orphaning)

2. Fixed Update function (resource_dataset.go)

• Applied the same pattern to the Update function for consistency.

3. Updated documentation (docs/resources/dataset.md)

• Added missing kind field to the documentation.