Add webpack's maxWorkers option to rspack's project configuration

[dgmachado]

What problem does this feature solve?

The maxWorkers option can be configured in project.json file and consumed by the Webpack. It's desirable that this option is supported by Rspack.

maxWorkers
Number of workers to use for type checking. (defaults to # of CPUS).

What does the proposed API of configuration look like?

         "options": {
              ...,
              "maxWorkers": 1,
              "memoryLimit": 2048,
              "generatePackageJson": false,
              ...,
         }