aconfig: add namespace field to flag_declaration and parsed_flag

Add a new field to the proto messages flag_declaration and parsed_flag.

The new field will be used verbatim as a parameter when calling
DeviceConfig.getBoolean to read the value of a READ_WRITE flag. See the
DeviceConfig API for more info.

Note: not to be confused with the old namespace field, which has been
renamed to package.

Bug: 285211724
Test: atest aconfig.test
Change-Id: I2181be7b5e98fc334e5277fb5f7e386f1fe0b550
diff --git a/tools/aconfig/templates/rust.template b/tools/aconfig/templates/rust.template
index 81b407c..d914943 100644
--- a/tools/aconfig/templates/rust.template
+++ b/tools/aconfig/templates/rust.template
@@ -19,7 +19,7 @@
 {{- if parsed_flag.is_read_write -}}
 #[inline(always)]
 pub fn r#{parsed_flag.name}() -> bool \{
-    flags_rust::GetServerConfigurableFlag("{package}", "{parsed_flag.name}", "false") == "true"
+    flags_rust::GetServerConfigurableFlag("{parsed_flag.device_config_namespace}", "{parsed_flag.device_config_flag}", "false") == "true"
 }
 
 {{ endif -}}