Reproduce Repository X-Ray functionality - Introduce lock file classes

What does this MR do and why?

Context

In #474306 (comment 2025085630), we decided to migrate the Repository X-Ray functionality into the GitLab Rails monolith. This gives us two main benefits: (i) it will eventually allow us to run the service outside of the CI pipeline, and (ii) we can maintain the parsing logic centrally so that other domains can utilize it.

This MR

This MR is the first step in the migration progress. It introduces the LockFiles::Base class where the intention is for each lock file type to be represented by a child class. The RubyGems child class serves as an example of the implementation.

Next Steps: Eventually we will add all the languages/lock files currently supported in Repository X-Ray. Then we will introduce a lock file parser class that utilizes these LockFiles::Base child classes.

POC: For a more complete picture of the overall implementation, see: Draft: POC - Reproduce base functionality of Re... (!162125 - closed)

Resolves part of #476177 (closed).

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #476177 (closed)

ee/lib/ai/context/dependencies/lock_files/base.rb

@@ -11,7 +11,10 @@ module LockFiles
         class Base
           include Gitlab::Utils::StrongMemoize
 
-          attr_reader :path
+          # This value is supposed to indicate the version of Repository X-Ray we are using;
+          # however, it's not applicable here so we just set it to a placeholder value.
+          # It may be removed entirely in https://gitlab.com/gitlab-org/gitlab/-/issues/479185.
+          SCANNER_VERSION = '0.0.0'
 
           Lib = Struct.new(:name, :version, keyword_init: true)
 
@@ -19,10 +22,14 @@ def self.file_name_glob
             raise NotImplementedError
           end
 
-          def self.lang
+          def self.lang_name
             raise NotImplementedError
           end
 
+          def self.lang
+            CodeSuggestions::ProgrammingLanguage::LANGUAGE_XRAY_NAMING[lang_name]
+          end
+
           def self.matches?(path)
             File.fnmatch?("**/#{file_name_glob}", path, File::FNM_PATHNAME | File::FNM_DOTMATCH)
           end
@@ -42,6 +49,7 @@ def parse!
             error('format not recognized or dependencies not present') if libs.blank? && errors.empty?
           end
 
+          # This hash matches the current XrayReport payload schema
           def payload
             return unless libs.present?
 
@@ -49,15 +57,10 @@ def payload
               libs: formatted_libs,
               checksum: checksum,
               fileName: path,
-              scannerVersion: '0.0.0' # To match current Repository X-Ray payload schema
+              scannerVersion: SCANNER_VERSION
             }
           end
 
-          def checksum
-            Digest::SHA256.hexdigest(content)
-          end
-          strong_memoize_attr :checksum
-
           def valid?
             errors.empty?
           end
@@ -70,7 +73,7 @@ def error_message
 
           private
 
-          attr_reader :content, :libs, :errors
+          attr_reader :content, :path, :libs, :errors
 
           def extract_libs
             raise NotImplementedError
@@ -87,6 +90,11 @@ def formatted_libs
           def error(message)
             @errors << message
           end
+
+          def checksum
+            Digest::SHA256.hexdigest(content)
+          end
+          strong_memoize_attr :checksum
         end
       end
     end