[rubygems/rubygems] Lazily parse dependencies in EndpointSpecification

Since not every dependency gets referenced.

When resolving from scratch a Gemfile including only `"gem "rails", "~>
8.0.1"`, I get the following results:

### Before

Total allocated: 295.01 MB (3624335 objects)
Total retained:  119.31 MB (1364474 objects)

### After
Total allocated: 288.21 MB (3498515 objects)
Total retained:  119.10 MB (1357976 objects)

ruby/rubygems@61eee39d81

Co-authored-by: Samuel Giddins <[email protected]>

Author: 2 people

lib/bundler/endpoint_specification.rb

@@ -6,15 +6,17 @@ class EndpointSpecification < Gem::Specification
     include MatchRemoteMetadata
 
     attr_reader :name, :version, :platform, :checksum
-    attr_accessor :remote, :dependencies, :locked_platform
+    attr_writer :dependencies
+    attr_accessor :remote, :locked_platform
 
     def initialize(name, version, platform, spec_fetcher, dependencies, metadata = nil)
       super()
       @name         = name
       @version      = Gem::Version.create version
       @platform     = Gem::Platform.new(platform)
       @spec_fetcher = spec_fetcher
-      @dependencies = dependencies.map {|dep, reqs| build_dependency(dep, reqs) }
+      @dependencies = nil
+      @unbuilt_dependencies = dependencies
 
       @loaded_from          = nil
       @remote_specification = nil
@@ -31,6 +33,10 @@ def fetch_platform
       @platform
     end
 
+    def dependencies
+      @dependencies ||= @unbuilt_dependencies.map! {|dep, reqs| build_dependency(dep, reqs) }
+    end
+
     # needed for standalone, load required_paths from local gemspec
     # after the gem is installed
     def require_paths