Add isolated and swarming to .gitignore

This is follow up of
https://chromium-review.googlesource.com/c/chromium/src/+/1286748

Change-Id: Ie1187e045df9e6e943ba957bcd6f8ba7ade0ba07
Reviewed-on: https://chromium-review.googlesource.com/c/1293053
Commit-Queue: Marc-Antoine Ruel <maruel@chromium.org>
Reviewed-by: Marc-Antoine Ruel <maruel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601551}

tools/luci-go/.gitignore

 /isolate
 /isolate.exe
+/isolated
+/isolated.exe
 /linux64/isolate
 /mac64/isolate
+/swarming
+/swarming.exe
 /win64/isolate.exe
 .versions