Improve test builder

[ono-max]

There are 2 points I implemented.

1. Test builder don't capitalize the first letter of class name.

Now

# frozen_string_literal: true

require_relative '../support/test_case'

module DEBUGGER__
  class deletetest < TestCase
    def program
      <<~RUBY
        1| a = 1
        1| b = 2
        2| c = 3
        3| d = 4
      RUBY
    end

Expected

# frozen_string_literal: true

require_relative '../support/test_case'

module DEBUGGER__
  class Deletetest < TestCase
    def program
      <<~RUBY
        1| a = 1
        1| b = 2
        2| c = 3
        3| d = 4
      RUBY
    end

2. When the string "test" is in the prefix, it won't be removed.

Now

$ bin/gentest target.rb  -c deletetest -m test_delete_keeps_current_breakpoints_if_not_confirmed
...
appended: /Users/naotto/workspace/debug/test/tool/../debug/deletetest_test.rb
    method: test_delete_keeps_current_breakpoints_if_not_confirmed

Expected

$ bin/gentest target.rb  -c deletetest -m test_delete_keeps_current_breakpoints_if_not_confirmed
appended: /Users/naotto/workspace/debug/test/tool/../debug/delete_test.rb
    method: test_delete_keeps_current_breakpoints_if_not_confirmed