Support async evaluation for compiler hooks

Feature request

Add a new async compiler hook at the beginning of compiler initialization, or turn most of sync hooks like entryOption to async.

What is the expected behavior? A plugin should be able to perform asynchronous tasks at any hooks specially at compiler initialization and configuration.

What is motivation or use case for adding/changing the behavior? There is some cases that plugin needs to evaluate for example new entries and this must be asynchronous, today this cannot be done as per all the hooks before, including entryOption, are synchronous.

How should this be implemented in your opinion? Refactor related sync process to async.

Are you willing to work on this yourself? Yes.

[sokra]

Compiler initialization need to stay sync. You can add async logic to determine entries. This is even supported without plugins:

// webpack.config.js
module.exports = {
  entry: async () => {
    await doSomething();
    return { main: "./main.js" };
  }
}

[alexander-akait]

You can use https://github.com/webpack/webpack/blob/main/lib/index.js, i.e.

const DynamicEntryPlugin = require("./DynamicEntryPlugin");
new DynamicEntryPlugin(compiler.context, async () => {}).apply(compiler);

in your plugin and add entry dynamically