feat: add @rspack/core as an optional peer dependency

[chenjiahan]

Background

Rspack is a fast Rust-based web bundler and it is compatible with the architecture and ecosystem of webpack.

The react-refresh-webpack-plugin can be used with Rspack, but users will get a peer dependency warning:

 WARN  Issues with peer dependencies found
.
    └─┬ @pmmmwh/react-refresh-webpack-plugin 0.5.10
      └── ✕ missing peer webpack@">=4.43.0 <6.0.0"

Description

This PR adds @rspack/core as an optional peer dependency, and make webpack as an optional peer dependency too.

Related issues

• Add @rspack/core to the peer dependencies of html-webpack-plugin and react-refresh-webpack-plugin web-infra-dev/rspack#4537
• Add webpack as optional peer dependency webpack/webpack-dev-server#4776

[chenjiahan]

@pmmmwh Hi, If you have the time, could you review and provide some feedback 😄

[pmmmwh]

Hey, sorry that I couldn't give this a proper look previously - if the RSPack team is still interested in this I am willing to land this change in the next version 0.6.x