C++ codegen arrow serialize non-union components/datatypes without ne…

…sted rerun types (#2820)

* Part of #2647
* Next step after: #2766

### What

Generates serialization for all non-union components and datatypes
except for datatypes nested in structs & unions.
Uses new serialization methods for 2D & 3D point logging. Ergonomics are
pretty poor at this point, handling this will be a follow-up.

Commit history got a bit messy at some point - **not** recommending
commit by commit reviewing ;)

Next Steps:
* work towards Point2D roundtrip
   * builder methods on archetype
   * make logging on Recording stream nice'ish
   * basic testing
* serialize unions
* serialize datatypes nested in unions, structs and lists
* more testing & roundtripping

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested [demo.rerun.io](https://demo.rerun.io/pr/2820) (if
applicable)

- [PR Build Summary](https://build.rerun.io/pr/2820)
- [Docs
preview](https://rerun.io/preview/pr%3Aandreas%2Fcpp-codegen%2Farrow-serialize-structs/docs)
- [Examples
preview](https://rerun.io/preview/pr%3Aandreas%2Fcpp-codegen%2Farrow-serialize-structs/examples)

.clang-format

@@ -3,6 +3,8 @@ BasedOnStyle: Google
 # Make it slightly more similar to Rust.
 # Based loosely on https://gist.github.com/YodaEmbedding/c2c77dc693d11f3734d78489f9a6eea4
 AccessModifierOffset: -2
+AlignAfterOpenBracket: BlockIndent
+AllowAllArgumentsOnNextLine: false
 AllowShortBlocksOnASingleLine: false
 AllowShortCaseLabelsOnASingleLine: false
 AllowShortFunctionsOnASingleLine: Empty
@@ -19,9 +21,9 @@ InsertTrailingCommas: Wrapped
 MaxEmptyLinesToKeep: 1
 NamespaceIndentation: All
 PointerAlignment: Left
+ReflowComments: true
 SeparateDefinitionBlocks: Always
 SpacesBeforeTrailingComments: 1
-ReflowComments: true
 
 # Don't change include blocks, we want to control this manually.
 # Sorting headers however is allowed as all our headers should be standalone.

crates/re_types_builder/src/codegen/cpp/forward_decl.rs

@@ -37,6 +37,7 @@ pub struct ForwardDecls {
 }
 
 impl ForwardDecls {
+    #[allow(dead_code)]
     pub fn insert(&mut self, namespace: impl Into<String>, decl: ForwardDecl) {
         self.declarations_per_namespace
             .entry(namespace.into())

crates/re_types_builder/src/codegen/cpp/method.rs

@@ -3,7 +3,7 @@ use quote::quote;
 
 use crate::Docs;
 
-use super::{doc_comment, quote_docstrings, NEWLINE_TOKEN};
+use super::{quote_doc_comment, quote_docstrings, NEWLINE_TOKEN};
 
 #[derive(Default)]
 pub struct MethodDeclaration {
@@ -82,7 +82,7 @@ impl quote::ToTokens for MethodDocumentation {
         match self {
             Self::None => {}
             Self::String(s) => {
-                tokens.extend(doc_comment(s));
+                tokens.extend(quote_doc_comment(s));
             }
             Self::Docs(docs) => tokens.extend(quote_docstrings(docs)),
         }
@@ -125,12 +125,14 @@ impl Method {
                 #declaration {
                     #definition_body
                 }
+                #NEWLINE_TOKEN
             }
         } else {
             quote! {
                 #NEWLINE_TOKEN
                 #docs
                 #declaration;
+                #NEWLINE_TOKEN
             }
         }
     }