Add embot_hw_testpoint

[sgiraz]

What's new:

• A new embot::hw::testpoint is now available to be used for HW debugging on both CM7 and CM4 cores.

Usage:

// declare a TESTPOINT
embot::hw::TESTPOINT tp1 {embot::hw::TESTPOINT::one};

// init the testpoint
embot::hw::testpoint::init(tp1);

// trigger the testpoint using the available public methods (e.g. on, off, toggle)
embot::hw::testpoint::on(tp1);

// ... other code ...

// trigger the testpoint again
embot::hw::testpoint::off(tp1);

Note:

• Tested on AMC board
• With this tool, you can monitor the state of the pin connected to a test point on the oscilloscope while measuring the time/frequency at which the test point changes state.

cc @davidetome @Nicogene @mfussi66

[marcoaccame]

OK @sigraz, the embot::hw device is implemented correctly:

• one .h file w/ the API,
• one _bsp.h file w/ the description of the data structure needed to adapt pinout and else to a given board,
• one .cpp w/ the implemenation,
• one ._bsp.cpp file specific to a given board.