Add create-itk-wasm package

[thewtex]

In itk-wasm/packages/create-itk-wasm/

Generates the skeleton for project in a directory:

• package.json with build and bindgen commands
• CMakeLists.txt
• *.cxx

This is produced by a main bin script. Prompts for description, etc.

Select one or more pipeline types, i.e. text file, binary file, json file, image, mesh, etc. Create .cxx with pipeline, inputs, outputs, dispatch on input type for images, meshes.

Can be invoked by pnpm create.

[thewtex]

Initial support in #1061 .

Todos:

• Fix usage with Windows Git Bash.
• Add demo GIF to README.