Add yiisoft/file-router package

[vjik]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌

[what-the-diff]

PR Summary

• Introduction of 'file-router' in the Package Configuration
  The update includes adding a 'file-router' to a file named packages.php. With this addition, there will be an improvement in how files are managed and routed within the application. This can lead to a better organization of files and streamlined workflow.

• Modification in String Concatenation Method in Yii Developer Tool Style
  The changes in YiiDevToolStyle.php involve altering the way strings are connected. The revised approach would enhance the performance and readability of the code, potentially making debugging easier in future.