Issue #1992894 by vijaycs85: Provide config schema to views components in user module.

core/modules/user/config/schema/user.view.schema.yml

+# Schema for the views plugins of the User module.
+
+views.argument_validator.user:
+  type: mapping
+  label: 'User'
+  mapping:
+    type:
+      type: string
+      label: 'Type of user filter value to allow'
+    restrict_roles:
+      type: boolean
+      label: 'Restrict user based on role'
+    roles:
+      type: sequence
+      label: 'Restrict to the selected roles'
+      sequence:
+        - type: string
+          label: 'Role'
+
+views.argument_default.user:
+  type: mapping
+  label: 'User ID from URL'
+  mapping:
+    user:
+      type: boolean
+      label: 'Also look for a node and use the node author'
+
+views.argument_default.current_user:
+  type: boolean
+  label: 'User ID from logged in user'
+
+views.argument_default.node:
+  type: boolean
+  label: 'Content ID from URL'