changes FileHandle type on Windows (#24910)

On windows, `HANDLE` type values are converted to `syncio.FileHandle` in
`lib/std/syncio.nim`, `lib/pure/memfiles.nim` and `lib/pure/osproc.nim`.
`HANDLE` type is `void *` on Windows and its size is larger then `cint`.

https://learn.microsoft.com/en-us/windows/win32/winprog/windows-data-types

This PR change `syncio.FileHandle` type so that converting `HANDLE` type
to `syncio.FileHandle` doesn't lose bits.

We can keep `FileHandle` unchanged and change some of parameter/return
type from `FileHandle` to an type same size to `HANDLE`, but it is
breaking change.

lib/std/syncio.nim

@@ -40,9 +40,6 @@ type
                          ## at the end. If the file does not exist, it
                          ## will be created.
 
-  FileHandle* = cint ## The type that represents an OS file handle; this is
-                      ## useful for low-level file access.
-
   FileSeekPos* = enum ## Position relative to which seek should happen.
                       # The values are ordered so that they match with stdio
                       # SEEK_SET, SEEK_CUR and SEEK_END respectively.
@@ -50,6 +47,13 @@ type
     fspCur            ## Seek relative to current position
     fspEnd            ## Seek relative to end
 
+when defined(windows):
+  type FileHandle* = int
+    ## Windows `HANDLE` type, convertible to `winlean.Handle`.
+else:
+  type FileHandle* = cint ## The type that represents an OS file handle; this is
+                      ## useful for low-level file access.
+
 # text file handling:
 when not defined(nimscript) and not defined(js):
   # duplicated between io and ansi_c
@@ -310,12 +314,7 @@ elif defined(windows):
   proc getOsfhandle(fd: cint): int {.
     importc: "_get_osfhandle", header: "<io.h>".}
 
-  type
-    IoHandle = distinct pointer
-      ## Windows' HANDLE type. Defined as an untyped pointer but is **not**
-      ## one. Named like this to avoid collision with other `system` modules.
-
-  proc setHandleInformation(hObject: IoHandle, dwMask, dwFlags: WinDWORD):
+  proc setHandleInformation(hObject: FileHandle, dwMask, dwFlags: WinDWORD):
                            WinBOOL {.stdcall, dynlib: "kernel32",
                                   importc: "SetHandleInformation".}
 
@@ -361,7 +360,7 @@ proc getFileHandle*(f: File): FileHandle =
   ## Note that on Windows this doesn't return the Windows-specific handle,
   ## but the C library's notion of a handle, whatever that means.
   ## Use `getOsFileHandle` instead.
-  c_fileno(f)
+  FileHandle c_fileno(f)
 
 proc getOsFileHandle*(f: File): FileHandle =
   ## Returns the OS file handle of the file `f`. This is only useful for
@@ -390,7 +389,7 @@ when defined(nimdoc) or (defined(posix) and not defined(nimscript)) or defined(w
       flags = if inheritable: flags and not FD_CLOEXEC else: flags or FD_CLOEXEC
       result = c_fcntl(f, F_SETFD, flags) != -1
     else:
-      result = setHandleInformation(cast[IoHandle](f), HANDLE_FLAG_INHERIT,
+      result = setHandleInformation(f, HANDLE_FLAG_INHERIT,
                                     inheritable.WinDWORD) != 0
 
 proc readLine*(f: File, line: var string): bool {.tags: [ReadIOEffect],
@@ -423,12 +422,18 @@ proc readLine*(f: File, line: var string): bool {.tags: [ReadIOEffect],
       importc: "LocalFree", stdcall, dynlib: "kernel32".}
 
     proc isatty(f: File): bool =
+      # terminal module also has isatty
       when defined(posix):
         proc isatty(fildes: FileHandle): cint {.
           importc: "isatty", header: "<unistd.h>".}
-      else:
-        proc isatty(fildes: FileHandle): cint {.
+      elif defined(windows):
+        proc c_isatty(fildes: cint): cint {.
           importc: "_isatty", header: "<io.h>".}
+        proc isatty(fildes: FileHandle): cint =
+          c_isatty(cint(fildes))
+      else:
+        {.error: "isatty is not supported on your operating system!".}
+
       result = isatty(getFileHandle(f)) != 0'i32
 
     # this implies the file is open
@@ -769,10 +774,10 @@ proc open*(f: var File, filehandle: FileHandle,
   ## The passed file handle will no longer be inheritable.
   when not defined(nimInheritHandles) and declared(setInheritable):
     let oshandle = when defined(windows): FileHandle getOsfhandle(
-        filehandle) else: filehandle
+        cint filehandle) else: filehandle
     if not setInheritable(oshandle, false):
       return false
-  f = c_fdopen(filehandle, RawFormatOpen[mode])
+  f = c_fdopen(cint filehandle, RawFormatOpen[mode])
   result = f != nil
 
 proc open*(filename: string,