Add basic FIPS class

Adds a simple class for storing FIPS helpers, including an initial
.enabled? method that just references a feature flag for now.

Changelog: added

config/feature_flags/development/fips_mode.yml

+---
+name: fips_mode
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/81418/diffs?view=inline
+rollout_issue_url:
+milestone: '14.9'
+type: development
+group: group::source code
+default_enabled: false

config/initializers_before_autoloader/000_inflections.rb

@@ -40,4 +40,5 @@ ActiveSupport::Inflector.inflections do |inflect|
   inflect.acronym 'JH'
   inflect.acronym 'CSP'
   inflect.acronym 'VSCode'
+  inflect.acronym 'FIPS'
 end

lib/gitlab/fips.rb

+# rubocop: disable Naming/FileName
+# frozen_string_literal: true
+
+module Gitlab
+  class FIPS
+    # A simple utility class for FIPS-related helpers
+
+    class << self
+      # Returns whether we should be running in FIPS mode or not
+      #
+      # @return [Boolean]
+      def enabled?
+        Feature.enabled?(:fips_mode, default_enabled: :yaml)
+      end
+    end
+  end
+end
+
+# rubocop: enable Naming/FileName

spec/lib/gitlab/fips_spec.rb

+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe Gitlab::FIPS do
+  describe ".enabled?" do
+    subject { described_class.enabled? }
+
+    context "feature flag is enabled" do
+      it { is_expected.to be_truthy }
+    end
+
+    context "feature flag is disabled" do
+      before do
+        stub_feature_flags(fips_mode: false)
+      end
+
+      it { is_expected.to be_falsey }
+    end
+  end
+end