fix: populate ID field in ovh_cloud_project_storage resource

[fabiencastarede]

Description

Fixes the ovh_cloud_project_storage resource to properly populate the id field in Terraform state.

Problem

The ovh_cloud_project_storage resource declares an id attribute in its schema but never populates it, leaving it as null in the Terraform state. According to Terraform Plugin Framework
best practices, if an id attribute is declared in the schema, it should be populated.

This causes issues with:

• Tools and frameworks that expect a populated ID field in Terraform state
• Inconsistency with other resources in the provider (e.g., ovh_cloud_project_database properly populates its ID)
• User expectations when inspecting state files

Changes

• Add ovhtypes import for TfString type creation
• Populate ID in Create() function after resource creation
• Populate ID in Read() function after fetching resource details
• Populate ID in Update() function after updating resource
• ID format: service_name/region_name/name (matches the import format defined in ImportState())

Benefits

• Complies with Plugin Framework best practices
• Provides consistency across the provider
• Makes the ID format explicit and matches import expectations
• Improves tooling compatibility

Testing

Tested with:

• Resource creation ✅
• Resource updates ✅
• Resource deletion ✅
• Resource import ✅
• State inspection ✅

The existing acceptance tests continue to pass as they already use the correct import ID format (service_name/region_name/name).

Backward Compatibility

This change is backward compatible since the ID field was previously null. Adding a value doesn't break existing workflows.

[jrm-d]

Hello @fabiencastarede, thanks a lot for your contribution !
My only suggestion would be to update the related ovh/resource_cloud_project_storage_test.go in order to validate that id is populated with the adequate value