Resolve "Enhancement: Feature Flags"

Closes #153

TODO:

1. Don't forge to populate all env files across different platforms (gitlab, bitwarden, kubernetes cluster ...) with FEATURE_FLAG_FLOWS variable

NOTES:

1. Do we need to create a data migration for populate existing Workspace records with default non-dict value for feature_flags field?

Summary by CodeRabbit

Release Notes

• New Features

  • Introduced a new feature flag (FEATURE_FLAG_FLOWS) to enable or disable experimental features for workspaces.
  • Conditional rendering of "Guided conversations" option based on the feature flag in the onboarding process.

• Improvements

  • Enhanced error handling for workspace deletion.
  • Improved model definitions for clarity and consistency, including new enumeration values for plans.

• Bug Fixes

  • Corrected formatting issues in environment variable declarations and ensured proper alignment.

• Documentation

  • Updated help texts for new and existing fields to provide better clarity on their usage.