Enable stringify_values option for hash config settings

What does this merge request do and why?

Fixes hash config type to properly stringify values, issue #3074 (closed)

The hash_setting method now supports a stringify_values parameter that converts all hash values to strings. This is particularly useful for environment variables where integer values from gdk.yml should be converted to strings.

Enable stringify_values option for hash config settings

Add stringify_values parameter to hash_setting method to converthash values to strings. This ensures environment variables withinteger values in gdk.yml are properly converted to strings.

How to set up and validate locally

1. Add env configurations that contain integers to gdk.yml
2. Run gdk config get env and you will see all the integers are now converted to string
3. Running rails console does not throw a type error anymore

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This MR references an issue describing the change.
• This change is backward compatible. If not, include steps to communicate to users.
• Tests added for new functionality. If not, raise an issue to follow-up.
• Observability added/updated (logging, metrics, tracing).
• Documentation added/updated.
• Announcement added for notable changes.
• gdk doctor test added.

Closes #3074 (closed)