Add single signal debouncer

[apcountryman]

Add single signal debouncer (::picolibrary::Debouce::Single_Signal_Debouncer).

• [x] The Single_Signal_Debouncer class should be defined in the include/picolibrary/debouce.h/source/picolibrary/debouce.cc header/source file pair
• [x] The Single_Signal_Debouncer class should have automated tests
• [x] The Single_Signal_Debouncer class should have the following template arguments:
  • [x] typename Samples: The unsigned integer type used to hold a signal sample stream
  • [x] std::uint_fast8_t SAMPLES: The number of signal samples to use to determine whether the signal state is stable
• [x] The Single_Signal_Debouncer class should support the following operations:
  • [x] constexpr Single_Signal_Debouncer( bool is_high ) noexcept;
  • [x] constexpr Single_Signal_Debouncer( Single_Signal_Debouncer && source ) noexcept = default;
  • [x] constexpr Single_Signal_Debouncer( Single_Signal_Debouncer const & source ) noexcept = default;
  • [x] ~Single_Signal_Debouncer() noexcept = default;
  • [x] constexpr auto operator=( Single_Signal_Debouncer && expression ) noexcept -> Single_Signal_Debouncer & = default;
  • [x] constexpr auto operator=( Single_Signal_Debouncer const & expression ) noexcept -> Single_Signal_Debouncer & = default;
  • [x] void debounce( bool is_high ) noexcept;: Update the debouncer with a new sample
  • [x] auto is_high() const noexcept -> bool;: Check if the debounced signal is in the high state
  • [x] auto is_low() const noexcept -> bool;: Check if the debounced signal is in the low state
• [x] Documentation