feat: Add message for marketplace disabled by enterprise group

Issue: Show extensions marketplace disabled message wh... (#382)

Description

This MR supports Add Enterprise-User group opt-in for Extensions... (&14604) by adding a specific message whenever the Web IDE receives the enterprise_group_disabled reason (see relevant BE code).

Screenshots

Using the Example App (only uses test values):

disabled_enterprise_group_demo

Using the package from this MR pipeline in the main project with changes from gitlab!161819 (merged):

web_ide_disabled_enterprise_group_integration_demo