Fix file_get_contents() error in tld command
Fix file_get_contents() error in tld command

When we added the `proxy` feature in https://github.com/laravel/valet/pull/913 we inadvertently broke the `tld` command.
It was concatenating old+new tld when searching for existing configs, thus it couldn't find the correct file, which triggered the reported error.

Fixes #984

This PR fixes the lookup by allowing the correct intended lookup tld to be passed in. It also checks that the file exists before trying to read it.

laravel/valet,laravel/valet,laravel/valet