aconfig: rename namespace -> package

What used to be referred to as a namespace is now called a package.

This CL is a semantic change only.

Bug: 285000854
Test: m nothing
Test: atest aconfig.test
Change-Id: If3fca67c415af75b44f316e16666b97089407069
diff --git a/tools/aconfig/templates/rust.template b/tools/aconfig/templates/rust.template
index d7f4e8d..a3c58c0 100644
--- a/tools/aconfig/templates/rust.template
+++ b/tools/aconfig/templates/rust.template
@@ -16,7 +16,7 @@
 {{- if parsed_flag.is_read_write -}}
 #[inline(always)]
 pub fn r#{parsed_flag.fn_name}() -> bool \{
-    flags_rust::GetServerConfigurableFlag("{namespace}", "{parsed_flag.name}", "false") == "true"
+    flags_rust::GetServerConfigurableFlag("{package}", "{parsed_flag.name}", "false") == "true"
 }
 
 {{ endif -}}