[tools] Improve gcmole part I: command line

- Convert gcmole to python3-ish code
  - use local Path implementation for future full migration
- Use optparse and explicit arguments for gcmole
  - Add explicit directories flags
  - Use backwards compatible env vars as fallbacks
- Add gn target v8_gcmole_files to avoid issues with missing or
  incompatible generated files

Drive-by-fixes for running gcmole without ignored files:
- Disable gcmole in Isolate::UnwindAndFindHandle
- Partially disable gcmole in V8HeapExplorer::AddEntry

Bug: v8:10009
Change-Id: I5b4d1c6554db300190226361b6c518419109ff3d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3497320Reviewed-by: Liviu Rau <liviurau@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79348}

infra/mb/gn_isolate_map.pyl

@@ -60,7 +60,7 @@
     "type": "script",
   },
   "run-gcmole": {
-    "label": "//tools/gcmole:v8_run_gcmole",
+    "label": "//tools/gcmole:v8_gcmole_files",
     "type": "script",
   },
   "run-num-fuzzer": {

tools/BUILD.gn

@@ -11,7 +11,7 @@ group("gn_all") {
   data_deps = [
     ":v8_check_static_initializers",
     "debug_helper:v8_debug_helper",
-    "gcmole:v8_run_gcmole",
+    "gcmole:v8_gcmole_files",
     "jsfunfuzz:v8_jsfunfuzz",
   ]
 

tools/gcmole/BUILD.gn

@@ -4,11 +4,13 @@
 
 import("../../gni/v8.gni")
 
-group("v8_run_gcmole") {
+group("v8_gcmole_files") {
   testonly = true
-
+  data_deps = [
+    "../../:v8_dump_build_config",
+    "../../:v8_generated_cc_files",
+  ]
   data = [
-    "GCMOLE.gn",
     "gcmole.py",
     "gcmole-test.cc",
     "gcmole-tools/",
@@ -36,8 +38,6 @@ group("v8_run_gcmole") {
     "$target_gen_dir/../../torque-generated/",
   ]
 
-  deps = [ "../../:run_torque" ]
-
   if (v8_gcmole) {
     # This assumes gcmole tools have been fetched by a hook
     # into v8/tools/gcmole/gcmole_tools.

tools/gcmole/GCMOLE.gn

-action("gcmole") {
-  sources = [
-    ### gcmole(all) ###
-    "tools/gcmole/gcmole-test.cc",
-  ]
-}