pw_protobuf_compiler: Rename generated GN targets

This updates generated protobuf targets to use the format
<target>.<generator> instead of <target>_<generator> to improve
readability.

Change-Id: I52d1e398d5bbece7f79ae87e9a1df7fdce880a6b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/22222
Reviewed-by: Wyatt Hepler <hepler@google.com>
Reviewed-by: Armando Montanez <amontanez@google.com>
Commit-Queue: Alexei Frolov <frolv@google.com>
diff --git a/pw_rpc/BUILD.gn b/pw_rpc/BUILD.gn
index 26a0042..b524080 100644
--- a/pw_rpc/BUILD.gn
+++ b/pw_rpc/BUILD.gn
@@ -67,7 +67,7 @@
 pw_source_set("common") {
   public_configs = [ ":default_config" ]
   public_deps = [
-    ":protos_pwpb",
+    ":protos.pwpb",
     "$dir_pw_containers:intrusive_list",
     dir_pw_assert,
     dir_pw_bytes,
@@ -221,7 +221,7 @@
 
 pw_test("service_test") {
   deps = [
-    ":protos_pwpb",
+    ":protos.pwpb",
     ":server",
     dir_pw_assert,
   ]
@@ -246,7 +246,7 @@
 
 pw_test("server_test") {
   deps = [
-    ":protos_pwpb",
+    ":protos.pwpb",
     ":server",
     ":test_utils",
     dir_pw_assert,