consolidate some of the logic around checking if a file is a res file or not

Author: zth

analysis/src/Files.ml

@@ -95,3 +95,5 @@ let rec collect ?(checkDir = fun _ -> true) path test =
       |> List.concat
     else []
   | _ -> if test path then [path] else []
+
+let isResFile path = exists path && Filename.check_suffix path ".res"

analysis/src/Hint.ml

@@ -89,7 +89,7 @@ let inlay ~path ~pos ~maxLength ~debug =
     Ast_iterator.default_iterator.value_binding iterator vb
   in
   let iterator = {Ast_iterator.default_iterator with value_binding} in
-  (if Files.exists path && Filename.check_suffix path ".res" then
+  (if Files.isResFile path then
    let parser =
      Res_driver.parsingEngine.parseImplementation ~forPrinter:false
    in
@@ -150,7 +150,7 @@ let codeLens ~path ~debug =
   let iterator = {Ast_iterator.default_iterator with value_binding} in
   (* We only print code lenses in implementation files. This is because they'd be redundant in interface files,
      where the definition itself will be the same thing as what would've been printed in the code lens. *)
-  (if Files.exists path && Filename.check_suffix path ".res" then
+  (if Files.isResFile path then
    let parser =
      Res_driver.parsingEngine.parseImplementation ~forPrinter:false
    in

analysis/src/SemanticTokens.ml

@@ -431,7 +431,7 @@ let command ~debug ~emitter ~path =
     }
   in
 
-  if Filename.check_suffix path ".res" then (
+  if Files.isResFile path then (
     let parser =
       Res_driver.parsingEngine.parseImplementation ~forPrinter:false
     in

analysis/src/Xform.ml

@@ -302,7 +302,7 @@ let parse ~filename =
 
 let extractCodeActions ~path ~pos ~currentFile ~debug =
   match Cmt.fullFromPath ~path with
-  | Some full when Filename.check_suffix currentFile ".res" ->
+  | Some full when Files.isResFile currentFile ->
     let structure, printExpr, printStructureItem =
       parse ~filename:currentFile
     in