[Feature]: should not fallback to liveReload when liveReload is disabled

[9aoy]

What problem does this feature solve?

Currently, if HMR cannot be used in certain scenarios, it will automatically fallback to liveReload in Rsbuild.

But we don't want to fallback to liveReload when liveReload is disabled, which is useful for users to debug some hmr errors.

What does the proposed API look like?

When hmr is broken, page reloading will not be triggered. The configuration is as follows:

export default {
  dev: {
    hmr:true,
    liveReload: false,
  },
};