[fuchsia] Rename fuchsia_package() rule to cr_fuchsia_package().

Fuchsia's SDK will soon provide GN rules include one for declaring
fuchsia package targets. Since the SDK-provided rule works differently
from the Chromium one but is called fuchsia_package(), we need to rename
the Chromium rule to avoid them clashing.

Bug: 1050703
Change-Id: I08c14069d98df07f78e9ef25bc2c234a825d5ebb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2047033
Auto-Submit: Wez <wez@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740324}

diff --git a/testing/test.gni b/testing/test.gni
index 782228a..086b27da 100644
--- a/testing/test.gni
+++ b/testing/test.gni

@@ -214,7 +214,7 @@
       deps = [ "//testing/buildbot/filters:fuchsia_filters" ]
     }
 
-    fuchsia_package(_pkg_target) {
+    cr_fuchsia_package(_pkg_target) {
       testonly = true
       forward_variables_from(invoker, [ "manifest" ])
       binary = ":$_exec_target"