schema fixups

Cherry-picked by eric with several changes.

- The fixups of missing bits of schema-schema are a fair cop.

- Several critical typos in the example.ipldsch.json file are fixed.

- I tweaked the syntax for aliases in the example file; we've had the
  idea since this was originally posted of putting representational
  concerns that are clearly associated with a field inline with the
  fields for convenience, but in parens to distinguish that they're
  indeed representation concerns rather than type/cardinality concerns,
  so this is the expression of that idea.

- I actually walked back the removal of representation blocks in the
  json.  There's probably valid considerations to be made on that, but
  it deserves separate handling.  (Disconcertingly, I actually added
  two *new* representation blocks that seem to previously have been
  missing due to typos.)

Any new errors are presumably mine.

Original: https://github.com/ipld/go-ipld-prime/pull/10

typed/declaration/examples.ipldsch

@@ -2,10 +2,8 @@
 type ExampleWithNullable map {String : nullable String}
 
 type ExampleWithAnonDefns struct {
-	fooField optional {String:String}
+	fooField optional {String:String} (alias "foo_field")
 	barField nullable {String:String}
 	bazField {String : nullable String}
 	wozField {String:[nullable String]}
-} representation map (
-	fooField: alias="foo_field"
-)
+} representation map

typed/declaration/examples.ipldsch.json

@@ -10,35 +10,35 @@
 			"kind": "struct",
 			"fields": {
 				"fooField": {
-					"valueType": {
-						"type": "map",
+					"type": {
+						"kind": "map",
 						"keyType": "String",
 						"valueType": "String"
 					},
 					"optional": true
 				},
 				"barField": {
-					"valueType": {
-						"type": "map",
+					"type": {
+						"kind": "map",
 						"keyType": "String",
 						"valueType": "String"
 					},
 					"nullable": true
 				},
 				"bazField": {
-					"valueType": {
-						"type": "map",
+					"type": {
+						"kind": "map",
 						"keyType": "String",
 						"valueType": "String",
 						"valueNullable": true
 					}
 				},
 				"wozField": {
-					"valueType": {
-						"type": "map",
+					"type": {
+						"kind": "map",
 						"keyType": "String",
 						"valueType": {
-							"type": "list",
+							"kind": "list",
 							"valueType": "String",
 							"valueNullable": true
 						}

typed/declaration/schema-schema.ipldsch.json

@@ -37,6 +37,22 @@
 				}
 			}
 		},
+		"TypeKind": {
+			"kind": "enum",
+			"members": {
+				"bool": null,
+				"string": null,
+				"bytes": null,
+				"int": null,
+				"float": null,
+				"map": null,
+				"list": null,
+				"link": null,
+				"union": null,
+				"struct": null,
+				"enum": null
+			}
+		},
 		"RepresentationKind": {
 			"kind": "enum",
 			"members": {
@@ -128,6 +144,13 @@
 				}
 			}
 		},
+		"TypeLink": {
+			"kind": "struct",
+			"fields": {},
+			"representation": {
+				"map": {}
+			}
+		},
 		"TypeUnion": {
 			"kind": "struct",
 			"fields": {
@@ -176,6 +199,9 @@
 						"valueType": "TypeName"
 					}
 				}
+			},
+			"representation": {
+				"map": {}
 			}
 		},
 		"UnionRepresentation_Inline": {
@@ -191,6 +217,9 @@
 						"valueType": "TypeName"
 					}
 				}
+			},
+			"representation": {
+				"map": {}
 			}
 		},
 		"TypeStruct": {