Refactor attribute macro codegen (#2126)

* refactor: rust Attribute codegen

* update: post-refactor usage of Attribute in codegen
add: more attribute tests
update: don't render attributes missing required args

* fix: Python Server codegen broken by Attribute refactor

* fix: Python Server codegen broken by extra `:W`

* remove: TODOs

* update: codegen code to use new attribute syntax

* fix: RustMetadata creation in ConstrainedBlobGenerator