Rename function, type_inside_typeguard

Summary:
I didn't find `typeguard_annotation` to be a very descriptive name,
especially inside of the `Type` module which has tons of helpers that
do various things (often they *construct* a type, and as a result the old
name kind of sounded like it was a smart constructor which it isn't, it's
actually deconstructing)

Reviewed By: grievejia

Differential Revision: D59594270

fbshipit-source-id: 5e967e53087365505336d01835a946a384e80beb

source/analysis/type.ml

@@ -4581,7 +4581,7 @@ let expression_contains_any expression =
   |> List.exists ~f:(Hashtbl.mem primitives_with_any_map)
 
 
-let typeguard_annotation = function
+let type_inside_typeguard = function
   | Parametric
       {
         name = "typing.TypeGuard" | "typing_extensions.TypeGuard";

source/analysis/type.mli

@@ -564,7 +564,7 @@ val is_untyped : t -> bool
 
 val contains_variable : t -> bool
 
-val typeguard_annotation : t -> t option
+val type_inside_typeguard : t -> t option
 
 val parameters : t -> Parameter.t list option
 

source/analysis/typeCheck.ml

@@ -4156,7 +4156,7 @@ module State (Context : Context) = struct
         { arguments = { Call.Argument.name = None; value = { Node.value = Name name; _ } } :: _; _ }
       when is_simple_name name -> (
         let { TypeInfo.Unit.annotation = callee_type; _ } = resolve_expression ~resolution test in
-        match Type.typeguard_annotation callee_type with
+        match Type.type_inside_typeguard callee_type with
         | Some guard_type ->
             let resolution = refine_local ~name (TypeInfo.Unit.create_mutable guard_type) in
             Value resolution