Feature: Need a label fields for namespace during the creation of namespace

[YashasviDevtron]

🔖 Feature description

Add a field for specifying labels during the creation of namespaces and environments in Devtron. This feature will allow users to apply necessary labels, directly during the creation process.

🎤 Pitch / Usecases

The client uses Istio for traffic routing and require a label (istio-enabled: true) at the namespace level. Currently, we do not support specifying labels when creating namespaces or environments, which can lead to issues if labels are missed.

🔄️ Alternative

Have to manually apply labels to namespaces after creation

👀 Have you spent some time to check if this issue has been raised before?

• [X] I checked and didn't find similar issue

🏢 Have you read the Code of Conduct?

• [X] I have read the Code of Conduct