Role Assignment - Treat name as case insensitive

When the wrong case is used for a role name, e.g. acrpull instead of the
correct AcrPull, azure will accept the request and return the correct
casing. This results in Terraform believing it needs to update the
resource incorrectly.

azurerm/resource_arm_role_assignment.go

@@ -50,12 +50,13 @@ func resourceArmRoleAssignment() *schema.Resource {
 			},
 
 			"role_definition_name": {
-				Type:          schema.TypeString,
-				Optional:      true,
-				Computed:      true,
-				ForceNew:      true,
-				ConflictsWith: []string{"role_definition_id"},
-				ValidateFunc:  validateRoleDefinitionName,
+				Type:             schema.TypeString,
+				Optional:         true,
+				Computed:         true,
+				ForceNew:         true,
+				ConflictsWith:    []string{"role_definition_id"},
+				DiffSuppressFunc: suppress.CaseDifference,
+				ValidateFunc:     validateRoleDefinitionName,
 			},
 
 			"principal_id": {