Reorganize output_tests for structs

As I added more and more cases, I found the dir structure hard to
navigate.  The new structure follows how you read a type:

   e.g. struct { F *string } -> struct/ptr_string

This exposed some redundant cases and some missing cases, too.

output_tests/struct/float64s/types.go

@@ -0,0 +1,7 @@
+package test
+
+type T struct {
+	F1 float64
+	F2 float64
+	F3 float64
+}

output_tests/struct/float64s_alias/types.go

@@ -1,6 +1,6 @@
 package test
 
-type A float32
+type A float64
 
 type T struct {
 	F1 A

output_tests/struct/int32/types.go

@@ -1,5 +1,5 @@
 package test
 
 type T struct {
-	F *int8
+	F int32
 }

output_tests/struct/int32_alias/types.go

@@ -1,6 +1,6 @@
 package test
 
-type A int8
+type A int32
 
 type T struct {
 	F A

output_tests/struct/map/int32_ptr_string/types.go

@@ -1,5 +1,5 @@
 package test
 
 type T struct {
-	F map[string]*int32
+	F map[int32]*string
 }

output_tests/struct/map/int32_string/types.go

@@ -1,5 +1,5 @@
 package test
 
 type T struct {
-	F map[string]int32
+	F map[int32]string
 }

output_tests/struct/map/int32_struct_strings/types.go

@@ -0,0 +1,9 @@
+package test
+
+type T struct {
+	F map[int32]struct {
+		F1 string
+		F2 string
+		F3 string
+	}
+}

output_tests/struct/ptr_float64_alias/types.go

@@ -1,7 +1,7 @@
 package test
 
-type A1 float32
-type A2 *float32
+type A1 float64
+type A2 *float64
 
 type T struct {
 	F1 *A1

output_tests/struct/ptr_int32/types.go

@@ -1,5 +1,5 @@
 package test
 
 type T struct {
-	F int8
+	F *int32
 }

output_tests/struct/ptrs_float64/types.go

@@ -0,0 +1,7 @@
+package test
+
+type T struct {
+	F1 *float64
+	F2 *float64
+	F3 *float64
+}

output_tests/structs/builtins/float32s/types.go

@@ -1,7 +0,0 @@
-package test
-
-type T struct {
-	F1 float32
-	F2 float32
-	F3 float32
-}

output_tests/structs/maps/builtins/float32/types.go

@@ -1,5 +0,0 @@
-package test
-
-type T struct {
-	F map[string]float32
-}