Replace MarkerShape with code-generated enum type

[emilk]

What

• Closes Use enum in codegen to specify constant-constants #3384

Also replaces Corner2D and ContainerKind, but those are blueprint only and thus not user facing (yet).

The user-facing code should stay mostly the same.

I also improved the generated documentation for all components and datatypes

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using newly built examples: app.rerun.io
  • Using examples from latest main build: app.rerun.io
  • Using full set of examples from nightly build: app.rerun.io
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• If applicable, add a new check to the release checklist!

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[emilk]

The old code had a bug, which defaulted the container_kind to the invalid value 0

[teh-cmc]

You shouldn't need an extra attribute to find the associated enum type.

field.type_().index() should give you the global index of the enum type associated with a given field, which you can then use to inspect it from the global enum registry.

E.g.:

diff --git a/crates/re_types_builder/src/objects.rs b/crates/re_types_builder/src/objects.rs
index 07d1f0fb38..e1d32f5516 100644
--- a/crates/re_types_builder/src/objects.rs
+++ b/crates/re_types_builder/src/objects.rs
@@ -795,6 +795,7 @@ impl ObjectField {
 
         let attrs = Attributes::from_raw_attrs(field.attributes());
 
+        dbg!(enums[field.type_().index() as usize]);
         let typ = if let Some(enum_type) = attrs.try_get(&fqname, crate::ATTR_ENUM_TYPE) {
             // Hack needed because flattbuffers report fields of enum types as integers.
             Type::Object(enum_type)

[teh-cmc]

Looks great except for that superfluous enum_type attribute and the miscellaneous hacks that come with it.

[teh-cmc]

why unreleased?

[emilk]

The generated doclink changes from https://docs.rs/re_types/latest/re_types/components/struct.MarkerShape.html to https://docs.rs/re_types/latest/re_types/components/enum.MarkerShape.html which doesn't exist (yet)