feat(angular-standalone): split app.config.ts and main.ts

[rdlabo]

Followed angular-cli template:

• https://github.com/angular/angular-cli/blob/main/packages/schematics/angular/application/files/standalone-files/src/main.ts.template
• https://github.com/angular/angular-cli/blob/main/packages/schematics/angular/application/files/standalone-files/src/app/app.config.ts.template

This allows for automatic writing of the ng add command.