schema: Implement DeprecationMessage for resources, data sources, and provider (#140)

Author: austinvalle

.changes/unreleased/ENHANCEMENTS-20240515-100422.yaml

@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: 'schema: Added `Description`, `MarkdownDescription` and `DeprecationMessage`
+  fields to resource, data source and provider schemas'
+time: 2024-05-15T10:04:22.078016-04:00
+custom:
+  Issue: "112"

internal/cmd/testdata/custom_and_external/all_output/default_pkg_name/datasource_example/example_data_source_gen.go

@@ -728,6 +728,7 @@
             }
           }
         ],
+        "deprecation_message": "This data source is deprecated!",
         "description": "\"Example\" datasource",
         "markdown_description": "\"Example\" _datasource_"
       }
@@ -1055,6 +1056,7 @@
           }
         }
       ],
+      "deprecation_message": "This provider is deprecated!",
       "description": "\"Example\" provider",
       "markdown_description": "\"Example\" _provider_"
     }
@@ -1435,6 +1437,7 @@
             }
           }
         ],
+        "deprecation_message": "This resource is deprecated!",
         "description": "\"Example\" resource",
         "markdown_description": "\"Example\" _resource_"
       }