[plugins] Support usecase of copying composer.json & composer.lock and redownloading whole plugin vendor.
[plugins] Support usecase of copying composer.json & composer.lock and redownloading whole plugin vendor.

This was not working previously because installation from lockfile does not give priority to the installer plugin, resulting in missing packages when composer checks
lockfile consistency. Now, the files are overwritten with a require of the installer first and then restored after the installer is installed.

vierbergenlars/authserver,vierbergenlars/authserver,vierbergenlars/authserver,vierbergenlars/authserver