BitArray.to_s should output the same format as Int.to_s

[dukenguyenxyz]

Currently BitArray.to_s is outputting in the format BitArray[00000]

https://github.com/crystal-lang/crystal/blob/f0901e1c825de1095d77998ffe8890bfca66def0/src/bit_array.cr#L212-L226

It would be more convenient and make more sense to have the output format similar to Int.to_s - so that it can be converted from a base 2 digit into a number of a different base, i.e.

 def to_s(io : IO) : Nil 
   each do |value| 
     io << (value ? '1' : '0') 
   end 
 end 

If we want the string representation explicitly stated in the string, then we can use .inspect (keep the current implementation):

  def inspect(io : IO) : Nil
    io << "BitArray["
    to_s(io)
    io << ']'
  end

[asterite]

Even though I think it's a good idea to have a way to format it like that, I don't think the default should be that. If you see "1001" in the output of "to_s" you might think it's a number, when it's not.

[straight-shoota]

Providing an unambiguous representation is #inspect's job. #to_s is supposed to provide a natural representation. A series of 1 and 0 seems like a very natural representation to me. I'm not sure if that's definitely better for to_s, though. I don't think this type is used often for direct user presentation. So maybe it could help if you could tell a bit about your use case, @dukeraphaelng?