Rename factory functions from 'Create' to 'Make' (#3706)

Similar to #3705, we actually have a mix of `Make` and `Create` in
factory functions too, so this PR is normalizing on `Make`. It's
intended to be consistent with the naming choice for Carbon factory
functions.

Note, MakeSyntheticBlock is the only one I feel a little weird about
because llvm's own APIs use Create, and this is essentially wrapping
LLVM calls. But the flipside is it also feels like a vague line to draw,
when we also differ from LLVM coding style in other ways.

common/indirect_value_test.cpp

@@ -35,7 +35,7 @@ struct NonMovable {
 
 TEST(IndirectValueTest, Create) {
   IndirectValue<NonMovable> v =
-      CreateIndirectValue([] { return NonMovable(42); });
+      MakeIndirectValue([] { return NonMovable(42); });
   EXPECT_EQ(v->i, 42);
 }
 
@@ -45,7 +45,7 @@ auto GetIntReference() -> const int& {
 }
 
 TEST(IndirectValueTest, CreateWithDecay) {
-  auto v = CreateIndirectValue(GetIntReference);
+  auto v = MakeIndirectValue(GetIntReference);
   EXPECT_TRUE((std::is_same_v<decltype(v), IndirectValue<int>>));
   EXPECT_EQ(*v, 42);
 }