Move third-party/glob_defs.bzl to shim_et (#9140)

Summary:As titled. Doing this so that `glob_defs.bzl` can be used by
other TARGETS files outside of `third-party/`.

Test Plan: Rely on CI jobs

Reviewers: myuan

Subscribers:

Tasks:

Tags:

### Summary
[PLEASE REMOVE] See [CONTRIBUTING.md's Pull
Requests](https://github.com/pytorch/executorch/blob/main/CONTRIBUTING.md#pull-requests)
for ExecuTorch PR guidelines.

[PLEASE REMOVE] If this PR closes an issue, please add a `Fixes
#<issue-id>` line.

[PLEASE REMOVE] If this PR introduces a fix or feature that should be
the upcoming release notes, please add a "Release notes: <area>" label.
For a list of available release notes labels, check out
[CONTRIBUTING.md's Pull
Requests](https://github.com/pytorch/executorch/blob/main/CONTRIBUTING.md#pull-requests).

### Test plan
[PLEASE REMOVE] How did you test this PR? Please write down any manual
commands you used and note down tests that you have written if
applicable.

Author: larryliu0820

backends/xnnpack/third-party/xnnpack_src_defs.bzl

@@ -7,7 +7,7 @@ load(
     _XNNPACK_SRCS = "XNNPACK_SRCS",
 )
 load("//backends/xnnpack/third-party/XNNPACK/gen:microkernels.bzl", "prod_srcs_for_arch")
-load("//third-party:glob_defs.bzl", "subdir_glob")
+load("@fbsource//xplat/executorch/third-party:glob_defs.bzl", "subdir_glob")
 
 def define_xnnpack_build_src(xnnpack_build_src):
     return ["XNNPACK/{}".format(src) for src in xnnpack_build_src]

third-party/glob_defs.bzl renamed to shim_et/xplat/executorch/third-party/glob_defs.bzl

@@ -1,7 +1,7 @@
 load("@fbsource//xplat/executorch/build/runtime_wrapper.bzl", "runtime")
+load("@fbsource//xplat/executorch/third-party/glob_defs.bzl", "subdir_glob")
 load(":flatcc_defs.bzl", "define_flatcc_targets")
 load(":gflags.bzl", "define_gflags")
-load(":glob_defs.bzl", "subdir_glob")
 load(":gtest_defs.bzl", "define_gtest_targets")
 load(":prebuilt_python_defs.bzl", "add_prebuilt_python_library_targets")
 load("@prelude//rules.bzl", "prebuilt_cxx_library")