Implement rename me -> self (#2444)

Implements change proposed in #1382

Replaces #1624

explorer/testdata/struct/equality.carbon

@@ -13,11 +13,11 @@ package ExplorerTest api;
 
 // TODO: Implement this with some kind of reflection?
 external impl {.x: i32, .y: i32} as EqWith(Self) {
-  fn Equal[me: Self](other: Self) -> bool {
-    return me.x == other.x and me.y == other.y;
+  fn Equal[self: Self](other: Self) -> bool {
+    return self.x == other.x and self.y == other.y;
   }
-  fn NotEqual[me: Self](other: Self) -> bool {
-    return me.x != other.x or me.y != other.y;
+  fn NotEqual[self: Self](other: Self) -> bool {
+    return self.x != other.x or self.y != other.y;
   }
 }
 

explorer/testdata/struct/equality_false.carbon

@@ -11,11 +11,11 @@ package ExplorerTest api;
 
 // TODO: Implement this with some kind of reflection?
 external impl {.x: i32, .y: i32} as EqWith(Self) {
-  fn Equal[me: Self](other: Self) -> bool {
-    return me.x == other.x and me.y == other.y;
+  fn Equal[self: Self](other: Self) -> bool {
+    return self.x == other.x and self.y == other.y;
   }
-  fn NotEqual[me: Self](other: Self) -> bool {
-    return me.x != other.x or me.y != other.y;
+  fn NotEqual[self: Self](other: Self) -> bool {
+    return self.x != other.x or self.y != other.y;
   }
 }
 

explorer/testdata/struct/fail_equality_type.carbon

@@ -10,11 +10,11 @@ package ExplorerTest api;
 
 // TODO: Implement this with some kind of reflection?
 external impl {.x: i32, .y: i32} as EqWith(Self) {
-  fn Equal[me: Self](other: Self) -> bool {
-    return me.x == other.x and me.y == other.y;
+  fn Equal[self: Self](other: Self) -> bool {
+    return self.x == other.x and self.y == other.y;
   }
-  fn NotEqual[me: Self](other: Self) -> bool {
-    return me.x != other.x or me.y != other.y;
+  fn NotEqual[self: Self](other: Self) -> bool {
+    return self.x != other.x or self.y != other.y;
   }
 }
 

explorer/testdata/struct/field_convertible_to_type.carbon

@@ -11,7 +11,7 @@ package ExplorerTest api;
 
 class TypeLike {
   impl as ImplicitAs(Type) {
-    fn Convert[me: Self]() -> Type { return i32; }
+    fn Convert[self: Self]() -> Type { return i32; }
   }
   fn Make() -> Self { return {}; }
 }