Make all file access 64-bit (uint64_t)

This changes the types of a big number of variables.

General rules:
- Using `uint64_t` in general. We also considered `int64_t` but eventually
  settled on keeping it unsigned, which is also closer to what one would expect
  with `size_t`/`off_t`.
- We only keep `int64_t` for `seek_end` (takes a negative offset from the end)
  and for the `Variant` bindings, since `Variant::INT` is `int64_t`. This means
  we only need to guard against passing negative values in `core_bind.cpp`.
- Using `uint32_t` integers for concepts not needing such a huge range, like
  pages, blocks, etc.

In addition:
- Improve usage of integer types in some related places; namely, `DirAccess`,
  core binds.

Note:
- On Windows, `_ftelli64` reports invalid values when using 32-bit MinGW with
  version < 8.0. This was an upstream bug fixed in 8.0. It breaks support for
  big files on 32-bit Windows builds made with that toolchain. We might add a
  workaround.

Fixes #44363.
Fixes godotengine/godot-proposals#400.

Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>

platform/android/detect.py

@@ -278,6 +278,9 @@ def configure(env):
     )
     env.Append(CPPDEFINES=["NO_STATVFS", "GLES_ENABLED"])
 
+    if get_platform(env["ndk_platform"]) >= 24:
+        env.Append(CPPDEFINES=[("_FILE_OFFSET_BITS", 64)])
+
     env["neon_enabled"] = False
     if env["android_arch"] == "x86":
         target_opts = ["-target", "i686-none-linux-android"]