Add metric name suggestion to json schema

Update metric defnition json schema to include name attribute, and
apply validation that asserts that prompts has been resolved.

config/metrics/schema.json

@@ -5,6 +5,10 @@
     "key_path": {
       "type": "string"
     },
+    "name": {
+      "type": ["string", "null"],
+      "pattern": "^([a-z]+_)*[a-z]+$"
+    },
     "description": {
       "type": "string"
     },

spec/lib/gitlab/usage/metric_definition_spec.rb

@@ -16,7 +16,8 @@ RSpec.describe Gitlab::Usage::MetricDefinition do
       time_frame: 'none',
       data_source: 'database',
       distribution: %w(ee ce),
-      tier: %w(free starter premium ultimate bronze silver gold)
+      tier: %w(free starter premium ultimate bronze silver gold),
+      name: 'count_boards'
     }
   end
 
@@ -53,6 +54,7 @@ RSpec.describe Gitlab::Usage::MetricDefinition do
       :distribution       | nil
       :distribution       | 'test'
       :tier               | %w(test ee)
+      :name               | 'count_<adjective_describing>_boards'
     end
 
     with_them do