Adding or changing turbo-module templates

In addition to generating the bindings between Hermes and Rust, uniffi-bindgen-react-native generates the files needed to run this as a turbo-module. The list of files are documented elsewhere in this book.

Templates are written for Askama templating library.

Changing the templates for these files is relatively simple. This PR is a good example of adding a file.

• Template files are in the codegen/templates directory.
• Template configuration are in codegen/mod.rs file.

Adding a new template

1. Add new template to the codegen/templates directory.
2. Add a new RenderedFile struct, which specifies the template, and its path to the files module in codegen/mod.rs.
3. Add an entry to the list of generated files in this book.

The template context will have quite a lot of useful information data-structures about the project; the most prominent:

• ModuleMetadata, which is generated from the lib.a file from the uniffi contents of the Rust library.
• ProjectConfig which is the in-memory representation of the YAML configuration file.
• CrateMetadata which is data about the crate derived from cargo metadata.