ComponentBatch doesn't implement AsComponents anymore (#8820)

This makes it impossible to pass something implementing `ComponentBatch`
(i.e. some native data that knows how to serialized itself into arrow
component data) directly to `RecordingStream::log`.

This forces the caller to either..:
* explicitly opt into the low-level / component-level APIs via
`my_data.serialized()`, which expose further custom-tagging facilities,
or
* use the archetype-level APIs instead, which handle tagging
automatically.

Similarly, this removes all the legacy support infrastructure that was
needed to carry `ComponentBatch`es all the way to the logger:
* `log_component_batches`
* `AsComponents::as_component_batches`
* `ComponentBatchCow`, `ComponentBatchCowWithDescriptor`, ...
* etc

I think this is all that's needed in order to..:
* fix #8757

At the very least, it makes sure that existing code that used to log
`ComponentBatch`es directly breaks at compile-time.

Author: teh-cmc

crates/build/re_types_builder/src/codegen/rust/api.rs

@@ -185,7 +185,7 @@ fn generate_object_file(
     code.push_str("use ::re_types_core::SerializationResult;\n");
     code.push_str("use ::re_types_core::{DeserializationResult, DeserializationError};\n");
     code.push_str("use ::re_types_core::{ComponentDescriptor, ComponentName};\n");
-    code.push_str("use ::re_types_core::{ComponentBatch, ComponentBatchCowWithDescriptor, SerializedComponentBatch};\n");
+    code.push_str("use ::re_types_core::{ComponentBatch, SerializedComponentBatch};\n");
 
     // NOTE: `TokenStream`s discard whitespacing information by definition, so we need to
     // inject some of our own when writing to file… while making sure that don't inject
@@ -1174,7 +1174,7 @@ fn quote_trait_impls_for_archetype(obj: &Object) -> TokenStream {
 
     let all_component_batches = {
         std::iter::once(quote! {
-            Self::indicator().serialized()
+            Some(Self::indicator())
         })
         .chain(obj.fields.iter().map(|obj_field| {
             let field_name = format_ident!("{}", obj_field.name);
@@ -1244,9 +1244,9 @@ fn quote_trait_impls_for_archetype(obj: &Object) -> TokenStream {
             }
 
             #[inline]
-            fn indicator() -> ComponentBatchCowWithDescriptor<'static> {
-                static INDICATOR: #quoted_indicator_name = #quoted_indicator_name::DEFAULT;
-                ComponentBatchCowWithDescriptor::new(&INDICATOR as &dyn ::re_types_core::ComponentBatch)
+            fn indicator() -> SerializedComponentBatch {
+                #[allow(clippy::unwrap_used)] // There is no such thing as failing to serialize an indicator.
+                #quoted_indicator_name::DEFAULT.serialized().unwrap()
             }
 
             #[inline]
@@ -1665,8 +1665,7 @@ fn quote_builder_from_obj(reporter: &Reporter, objects: &Objects, obj: &Object)
                 I: IntoIterator<Item = usize> + Clone,
             {
                 let columns = [ #(#fields),* ];
-                let indicator_column = #indicator_column;
-                Ok(columns.into_iter().chain([indicator_column]).flatten())
+                Ok(columns.into_iter().flatten().chain([#indicator_column]))
             }
 
             #columns_unary_doc

crates/store/re_data_loader/src/loader_archetype.rs

@@ -220,7 +220,7 @@ fn load_video(
                 std::iter::once((video_timeline, time_column)).collect(),
                 [
                     (
-                        VideoFrameReference::indicator().descriptor().into_owned(),
+                        VideoFrameReference::indicator().descriptor.clone(),
                         video_frame_reference_indicators_list_array,
                     ),
                     (

crates/store/re_log_types/src/example_components.rs

@@ -67,6 +67,13 @@ impl MyPoints {
 impl re_types_core::Archetype for MyPoints {
     type Indicator = re_types_core::GenericIndicatorComponent<Self>;
 
+    fn indicator() -> SerializedComponentBatch {
+        use re_types_core::ComponentBatch as _;
+        // These is no such thing as failing to serialized an indicator.
+        #[allow(clippy::unwrap_used)]
+        Self::Indicator::default().serialized().unwrap()
+    }
+
     fn name() -> re_types_core::ArchetypeName {
         "example.MyPoints".into()
     }