Do not run sanity check on rails generate stimulus_reflex:config

If a sanity check fails, the user gets a hint to create the configuration file with
`rails generate stimulus_reflex:config`, however this command will also fail because it
will also run the sanity check. Therefore we have to bypass the sanity check if
the caller is a `generate_command`.

lib/stimulus_reflex/sanity_checker.rb

@@ -3,12 +3,22 @@
 class StimulusReflex::SanityChecker
   JSON_VERSION_FORMAT = /(\d+\.\d+\.\d+.*)"/
 
-  def self.check!
-    return if StimulusReflex.config.on_failed_sanity_checks == :ignore
+  class << self
+    def check!
+      return if StimulusReflex.config.on_failed_sanity_checks == :ignore
+      return if called_by_generate_command?
+
+      instance = new
+      instance.check_caching_enabled
+      instance.check_javascript_package_version
+    end
+
+    private
+
+    def called_by_generate_command?
+      caller.any? { |call| call.match("generate_command") }
+    end
 
-    instance = new
-    instance.check_caching_enabled
-    instance.check_javascript_package_version
   end
 
   def check_caching_enabled