Add BGNPCGN Dzongkha system 2010

[ronaldtse]

Originally by @manuel489 from https://github.com/interscript/interscript-ruby/pull/26

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From @manuel489

I used the following chart to find relevant unicode values: https://www.unicode.org/charts/PDF/U0F00.pdf

And the following link to convert them into characters: https://www.branah.com/unicode-converter

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From @ronaldtse

Currently failing on these tests:

  16) Interscript maps/bgnpcgn-dzo-Tibt-Latn-2010.yaml system test for {"source"=>"ཐྀམ་ཕུ", "expected"=>"Thimphu"}
      Failure/Error: expect(result).to eq(test["expected"])

        expected: "Thimphu"
             got: "thaྀm་phaུ"

        (compared using ==)
      # ./spec/interscript_spec.rb:13:in `block (5 levels) in <top (required)>'

  17) Interscript maps/bgnpcgn-dzo-Tibt-Latn-2010.yaml system test for {"source"=>"བཀྲ་ཤིས་གྱང་ཙེ", "expected"=>"Trashi Yangtse"}
      Failure/Error: output[pos, match.size] = result

      TypeError:
        no implicit conversion of Array into String
      # ./lib/interscript.rb:48:in `[]='
      # ./lib/interscript.rb:48:in `block in transliterate'
      # ./lib/interscript.rb:44:in `each'
      # ./lib/interscript.rb:44:in `transliterate'
      # ./spec/interscript_spec.rb:12:in `block (5 levels) in <top (required)>'

  18) Interscript maps/bgnpcgn-dzo-Tibt-Latn-2010.yaml system test for {"source"=>"སྟང་སི་སྦྱིས", "expected"=>"Tangsibji"}
      Failure/Error: expect(result).to eq(test["expected"])

        expected: "Tangsibji"
             got: "ྟng་ི་ྦྱི"

        (compared using ==)
      # ./spec/interscript_spec.rb:13:in `block (5 levels) in <top (required)>'

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From @manuel489

I think it is worth to say that I took these tests from the notes section of the PDF file. For example: