Add missing definitions for utility, math, and algorithm standard libraries (digest, forwardable, random-formatter, singleton, time, tsort)

[zonuexe]

Add missing methods, classes, and constants for digest, forwardable, random-formatter, singleton, time, and tsort.
Also refine Forwardable.debug and Forwardable.debug=.

Note: benchmark and bigdecimal-math have been excluded as they are in ALUMNI_STDLIBS and planned to be removed from the rbs repo.

Changes

Ruby Method	Change	C function
Digest::VERSION	Add constant VERSION	https://github.com/ruby/digest/blob/master/ext/digest/digest.c
Forwardable.debug	Return type untyped → boolish	https://github.com/ruby/forwardable/blob/master/lib/forwardable.rb
Forwardable.debug=	Return type T → void, accept boolish	https://github.com/ruby/forwardable/blob/master/lib/forwardable.rb
Random::Formatter::ALPHANUMERIC	Add constant ALPHANUMERIC	https://github.com/ruby/ruby/blob/v4.0.7/lib/random/formatter.rb
Singleton.module_with_class_methods	Add singleton method module_with_class_methods	https://github.com/ruby/singleton/blob/master/lib/singleton.rb
Singleton::VERSION	Add constant VERSION	https://github.com/ruby/singleton/blob/master/lib/singleton.rb
Time::VERSION	Add constant VERSION	https://github.com/ruby/time/blob/master/lib/time.rb
TSort::VERSION	Add constant VERSION	https://github.com/ruby/tsort/blob/master/lib/tsort.rb

[ksss]

benchmark and bigdecimal-math are planned to be removed from the rbs repo.
Please submit your requests to each gem.

rbs/lib/rbs/collection/config/lockfile_generator.rb

Lines 7 to 22 in 5a8d8ac

	ALUMNI_STDLIBS = {
	"mutex_m" => ">= 0.3.0",
	"abbrev" => nil,
	"base64" => nil,
	"benchmark" => nil,
	"bigdecimal" => nil,
	"csv" => nil,
	"kconv" => nil,
	"logger" => nil,
	"minitest" => nil,
	"net-smtp" => nil,
	"nkf" => nil,
	"observer" => nil,
	"cgi" => nil,
	"pstore" => nil,
	}

[zonuexe]

Thank you for the guidance! I have excluded benchmark and bigdecimal-math from this PR, keeping only digest, forwardable, random-formatter, singleton, time, and tsort. I will submit separate PRs to ruby/benchmark and ruby/bigdecimal.
Also updated constant assertions in test files to use assert_const_type.