Sort ls result ordered by anscestry

[neko314]

This PR suggests to improve ls command.

I changed these two points.

• I expect it to be the same as the result of the method search, but it is not.
• I want the output to be in the same order as the results of ancestors, but but in fact it is displayed in the order of modules->classes.

Example

Definitions are below; a little bit different from sample codes in #234, I added some modules and classes have the same methods.

class P
  def m() end
  def m2() end
end

class C < P
  def m1() end
  def m2() end
end

module M
  def m1() end
  def m3() end
end

module M2
  include M
  def m4() end
end

obj = C.new; obj.extend M2; def obj.m5() end;

Before

> ls obj
M#methods: m1  m3
M2#methods: m4
C.methods: m5
P#methods: m
C#methods: m1  m2

• m1 appears twice.
• obj.singleton_class.ancestors is [M2, M, C, P, Object, PP::ObjectMixin, Kernel, BasicObject]. I was a little confused the difference between my expectation and actual.

After

> ls obj
P#methods: m
C#methods: m2
M#methods: m1  m3
M2#methods: m4
C.methods: m5

[neko314]

CI failed https://github.com/ruby/irb/pull/245/checks?check_run_id=2867533381
This problem loooks to be resolved by #247

[aycabta]

😎