Test loader doesn't work : Critical dependency: the request of a dependency is an expression

まだ誰も着手していません。

With NodeJS v16.13.0 on Windows
```
$ npm run build && npx webpack --config test/config/javascript-obfuscator-loader.config.js --stats-error-details

> webpack-obfuscator@3.5.1 build
> npx tsc

asset index.js 1.13 KiB [emitted] [minimized] (name: index) 1 related asset
asset index-excluded.js 1.02 KiB [emitted] [minimized] (name: index-excluded) 1 related asset
runtime modules 211 bytes 2 modules
cacheable modules 2.78 KiB
./test/input/index.js 1.41 KiB [built] [code generated]
./test/input/index-excluded.js 245 bytes [built] [code generated]
./test/input/nested.js 1.13 KiB [built] [code generated]
./test/input/ sync 160 bytes [built] [code generated]

WARNING in ./test/input/index.js 1:1127-1152
Critical dependency: the request of a dependency is an expression
at CommonJsRequireContextDependency.getWarnings (xxx\webpack-obfuscator\node_modules\webpack\lib\dependencies\ContextDependency.js:91:18)
at Compilation.reportDependencyErrorsAndWarnings (xxx\webpack-obfuscator\node_modules\webpack\lib\Compilation.js:3131:24)
at xxx\webpack-obfuscator\node_modules\webpack\lib\Compilation.js:2728:28
at _next2 (eval at create (xxx\webpack-obfuscator\node_modules\tapable\lib\HookCodeFactory.js:33:10), :25:1)
at eval (eval at create (xxx\webpack-obfuscator\node_modules\tapable\lib\HookCodeFactory.js:33:10), :52:1)
at xxx\webpack-obfuscator\node_modules\webpack\lib\FlagDependencyExportsPlugin.js:385:11
at xxx\webpack-obfuscator\node_modules\neo-async\async.js:2830:7
at Object.each (xxx\webpack-obfuscator\node_modules\neo-async\async.js:2850:39)
at xxx\webpack-obfuscator\node_modules\webpack\lib\FlagDependencyExportsPlugin.js:361:18
at xxx\webpack-obfuscator\node_modules\neo-async\async.js:2830:7
```

レポートに記載されたコマンドを test/config/javascript-obfuscator-loader.config.js で再現し、test/input/index.js、test/input/index-excluded.js、test/input/nested.js を調査します。出力された critical-dependency 警告が loader の失敗であるかどうかを判断し、その結果に基づいて意図された loader テストの動作を確認し、完了を記録します。

索引モデルが issue の本文から書いたものです。