Change 'Create new config' command to create file in .devproxy folder at workspace root

[garrytrinder]

The 'Create new config' command should be updated to create the configuration file inside a .devproxy folder located at the root of the workspace, instead of its current location. This change will help in organizing config files and improve discoverability.

Acceptance Criteria:

• When the command is executed, the config file is placed in .devproxy at the workspace root.
• If the .devproxy folder does not exist, it should be created automatically.
• Update any relevant documentation or usage messages to reflect the new location.

Benefits:

• Better organization of config files
• Easier management and cleanup
• Aligns with common tool practices