fix: handling for overwrite class without json output

[ejseqera]

Fixes #170.

• Creates a separate instance of the SeqeraPlatform class for Overwrite to inherit without using the JSON option so we don't double up on -o json. The Overwrite class handles emitting output to JSON natively so we don't need this handling.
• Modified _execute_command to respect print_stdout setting when JSON output is enabled. Previously, stdout would always be printed when processing JSON output, regardless of the print_stdout flag. This change ensures consistent behavior between JSON and non-JSON output modes.