First step to rearrange files in tools folder (#60473)

Summary:
Changes including:
- introduced `linter/`, `testing/`, `stats/` folders in `tools/`
- move appropriate scripts into these folders
- change grepped references in the pytorch/pytorch repo

Next step
- introduce `build/` folder for build scripts

Pull Request resolved: https://github.com/pytorch/pytorch/pull/60473

Test Plan:
- CI (this is important b/c pytorch/test-infra also rely on some script reference.
- tools/tests/

Reviewed By: albanD

Differential Revision: D29352716

Pulled By: walterddr

fbshipit-source-id: bad40b5ce130b35dfd9e59b8af34f9025f3285fd

Makefile

@@ -26,7 +26,7 @@ SHELLCHECK_GHA_GENERATED_FOLDER=.shellcheck_generated_gha
 shellcheck-gha:
 	@$(RM) -r $(SHELLCHECK_GHA_GENERATED_FOLDER)
 	tools/extract_scripts.py --out=$(SHELLCHECK_GHA_GENERATED_FOLDER)
-	tools/run_shellcheck.sh $(SHELLCHECK_GHA_GENERATED_FOLDER)
+	tools/linter/run_shellcheck.sh $(SHELLCHECK_GHA_GENERATED_FOLDER)
 
 generate-gha-workflows:
 	.github/scripts/generate_ci_workflows.py