fix: Address conflict in boundary_scope data source schema (#492)

* fix: Modify error message

* refact: Rename keys for consistency

* fix: Use scope_id in boundary_scope

The examples for the boundary_scope data source suggest to use `parent_scope_id`, but the provider is actually expecting `scope_id`.

examples/data-sources/boundary_scope/data-source.tf

@@ -1,10 +1,10 @@
 # Retrieve the ID of a Boundary project
 data "boundary_scope" "org" {
-  name            = "SecOps"
-  parent_scope_id = "global"
+  name     = "SecOps"
+  scope_id = "global"
 }
 
 data "boundary_scope" "project" {
-  name            = "2111"
-  parent_scope_id = data.boundary_scope.id
+  name     = "2111"
+  scope_id = data.boundary_scope.id
 }