point Primer namespace to root

This resolves an Uninitialized Constant error coming from ruby, because
`ERBLint::Linter::Primer::` is a namespace that exists. This error was
not invoked before because the only liner in that namespace -
`ERBLint::Linter::Primer::Accessibility::TooltippedMigration` in the
`tooltipped_migration.rb` file - would load _after_
`argument_mappers/label.rb` and `label_component_migration_counter.rb`.

The introduction of
`ERBLint::Linter::Primer::Accessibility::DetailsMenuMigration` in the
`details_menu_migration.rb` file would load _before_
`label_component_migration_counter.rb`, populating the
`ERBLint::Linter::Primer` namespace, which then causes the failed scope
lookup.

Prepending `::` to these values tells ruby to always look in the root
scope, not any local constants.

lib/primer/view_components/linters/argument_mappers/label.rb

@@ -7,24 +7,24 @@ module Linters
     module ArgumentMappers
       # Maps classes in a label element to arguments for the Label component.
       class Label < Base
-        SCHEME_MAPPINGS = Primer::ViewComponents::Constants.get(
+        SCHEME_MAPPINGS = ::Primer::ViewComponents::Constants.get(
           component: "Primer::Beta::Label",
           constant: "SCHEME_MAPPINGS",
           symbolize: true
         ).freeze
 
-        SIZE_MAPPINGS = Primer::ViewComponents::Constants.get(
+        SIZE_MAPPINGS = ::Primer::ViewComponents::Constants.get(
           component: "Primer::Beta::Label",
           constant: "SIZE_MAPPINGS",
           symbolize: true
         ).freeze
 
-        DEFAULT_TAG = Primer::ViewComponents::Constants.get(
+        DEFAULT_TAG = ::Primer::ViewComponents::Constants.get(
           component: "Primer::Beta::Label",
           constant: "DEFAULT_TAG"
         ).freeze
 
-        INLINE_CLASS = Primer::ViewComponents::Constants.get(
+        INLINE_CLASS = ::Primer::ViewComponents::Constants.get(
           component: "Primer::Beta::Label",
           constant: "INLINE_CLASS"
         ).freeze

lib/primer/view_components/linters/label_component_migration_counter.rb

@@ -10,7 +10,7 @@ module Linters
     class LabelComponentMigrationCounter < BaseLinter
       include Autocorrectable
 
-      TAGS = Primer::ViewComponents::Constants.get(
+      TAGS = ::Primer::ViewComponents::Constants.get(
         component: "Primer::Beta::Label",
         constant: "TAG_OPTIONS"
       ).freeze