Add configuration file for setting default flags

[theopfr]

Description:

Similar to how bat (a cat clone with wings) handles it, a configuration file should be added to store default flags which will automatically be applied when executing somo.
This allows users who always want to run somo with, for example, --compact (or any other flag) to avoid typing it every time.

Features and requirements:

• Location:
  Config file should be stored at ~/.config/somo/config.
• Format:
  • Plain text
  • Each line is either:
    • blank
    • a comment (line starting with #, no inline comments)
    • a flag (e.g., --compact or --tcp)
  • Invalid flags should trigger a warning
• Commands:
  • --generate-config-file generates the config file at the default path, should not overwrite an existing file and should contain example flags commented out
  • --config-file prints the path to the config file
• Flag precedence:
  Flags provided explicitly on the CLI override flags loaded from the config file
• Programmatic integration:
  The flags from the config file should be parsed and added to argv before Clap processes them