Fix label requirement on Workflow creation page

When creating a workflow, there are two fields shown as required: ID and label. If none are filled, the user is unable to proceed and a validation warning is shown ("ID is required"). However, if the only the ID is filled the user can proceed as if the label field isn't required. Then in the general tab label is not required anymore.

Acceptance Criteria:

• A user should not be able to create a Workflow feature on Studio unless both required fields (ID and label) are filled.
• When trying to create a Workflow feature, if the ID field is filled but the label field isn't, a validation message should be shown. Example: "Workflow label is required".
• Label field is required in the workflow general tab.
• When an existing workflow did not have a label yet in the general tab, a validation error is shown: "Workflow label is empty".