[fuchsia] Add routing for tzdata-icu.

This allows us to move time zone information from /config/data to
/config/tzdata, and remove it from `config-data` package.

For the /config/tzdata placement on Fuchsia, see:
https://fuchsia.dev/fuchsia-src/concepts/process/namespaces?typical_directory_structure

Bug: b/315860162
Change-Id: I26728173205fc425a0b220c3e5c967fdcdcf43db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5112835
Reviewed-by: Zijie He <zijiehe@google.com>
Reviewed-by: Alex Gough <ajgo@chromium.org>
Commit-Queue: Filip Filmar <fmil@google.com>
Cr-Commit-Position: refs/heads/main@{#1236727}

fuchsia_web/webengine/web_engine_integration_tests.shard.test-cml

@@ -54,6 +54,13 @@
       to: "#realm_builder",
       subdir: "web_engine",
     },
+    {
+      directory: "tzdata-icu",
+      from: "parent",
+      rights: [ "r*" ],
+      to: "#realm_builder",
+    },
+
     {
       protocol: [
         "fuchsia.logger.LogSink",

fuchsia_web/webengine/web_instance-common.shard.cml

@@ -64,6 +64,16 @@
       availability: "optional",
     },
 
+    // Holds ICU time zone data files.
+    // See:
+    // https://fuchsia.dev/fuchsia-src/concepts/process/namespaces?typical_directory_structure
+    {
+      directory: "tzdata-icu",
+      rights: [ "r*" ],
+      path: "/config/tzdata/icu",
+      availability: "optional",
+    },
+
     // Temporary directory specified by WebInstanceHost.set_tmp_dir.
     {
       directory: "tmp",