Reland "Add luci-go tool to be fetched via CIPD"

This is a reland of 3bcc71d8

Original change's description:
> Add luci-go tool to be fetched via CIPD
> 
> Do not remove the adhoc mechanism on GCS that predates CIPD yet, as the recipes
> need to be updated.
> 
> Change analyze to not ignore changes to isolate.
> 
> R=tandrii@chromium.org
> 
> Bug: 851596
> Change-Id: Ic068db83dea4c3a0f17b55181de523b16c9838a5
> Reviewed-on: https://chromium-review.googlesource.com/1097623
> Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
> Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
> Reviewed-by: John Budorick <jbudorick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#569688}

Bug: 851596
Change-Id: I27382d97370376dcca8110c9225c16dada182256
Reviewed-on: https://chromium-review.googlesource.com/1125000Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Marc-Antoine Ruel <maruel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572435}

DEPS

@@ -346,6 +346,16 @@ deps = {
       'condition': 'checkout_nacl',
   },
 
+  'src/tools/luci-go': {
+      'packages': [
+        {
+          'package': 'infra/tools/luci/isolate/${{platform}}',
+          'version': 'git_revision:8b15ba47cbaf07a56f93326e39f0c8e5069c19e8',
+        },
+      ],
+      'dep_type': 'cipd',
+  },
+
   'src/third_party/SPIRV-Tools/src':
     Var('chromium_git') + '/external/github.com/KhronosGroup/SPIRV-Tools.git' + '@' + '9166854ac93ef81b026e943ccd230fed6c8b8d3c',
 
@@ -1708,6 +1718,7 @@ hooks = [
     ],
   },
   # Pull luci-go binaries (isolate, swarming) using checked-in hashes.
+  # TODO(maruel): Remove, https://crbug.com/851596
   {
     'name': 'luci-go_win',
     'pattern': '.',

testing/buildbot/trybot_analyze_config.json

@@ -32,8 +32,7 @@
       "testing/scripts/.*",
       "testing/test_env.py",
       "third_party/android_platform/development/scripts/.*",
-      "tools/clang/blink_gc_plugin/CMakeLists.txt",
-      "tools/luci-go/.*"
+      "tools/clang/blink_gc_plugin/CMakeLists.txt"
     ],
     "ignores": [
       "infra/config/recipes.cfg",

tools/luci-go/.gitignore

+/isolate
+/isolate.exe
 /linux64/isolate
 /mac64/isolate
 /win64/isolate.exe

tools/luci-go/OWNERS

-djd@chromium.org
 maruel@chromium.org
 tandrii@chromium.org
-tansell@chromium.org
 vadimsh@chromium.org

tools/luci-go/README.md

@@ -2,9 +2,4 @@
 
 Contains executable built out of
 https://chromium.googlesource.com/infra/luci/luci-go/+/master/client/cmd
-
-The binaries are retrieved from the following builders:
-
-- mac64: http://build.chromium.org/p/chromium.infra/builders/infra-continuous-mac-10.10-64/
-- linux64: http://build.chromium.org/p/chromium.infra/builders/infra-continuous-precise-64/
-- win64: http://build.chromium.org/p/chromium.infra/builders/infra-continuous-win-64/
+Mapped through CIPD.