src/corelibs/spi: Added the 3wire test with the TLE5012.

[Frederikwag]

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Description
Added the 3 wire test for SPI. 3 tests are executed:

• Verify if the sensor is responding
• Request angle data from the sensor using 3-wire SPI (16 bit
• Request temperature data from the sensor (8 bit)

Context
The test requires the sensor tlx5012. Later on, we need to "professionalize" it so that it communicates with another board. Setting up the XMC as slave is the critical part.

Important
Short-circuit MOSI and MISO in advance!
During the test, the magnet needs to be close to the sensor.

[LinjingZhang]

We have to check if we can test the 3Wire SPI without depending on the library...
Otherwise this test is out of scope of arduino-core-test.

[ederjc]

The test requires the sensor tlx5012. Later on, we need to "professionalize" it so that it communicates with another board. Setting up the XMC as slave is the critical part.

What keeps us from "professionalizing" it now?

As @LinjingZhang mentioned this is at the moment testing the sensor (can we include this in the sensor lib instead @OlafFilies?).

Still, a 3-wire SPI test for the cores should be developed.

[OlafFilies]

We can of course send this test to the tlx5012 lib, but it has yet no tests at all.
To test 3 wire SPI exactly what it says, 3 wires where MISO/MOSI of both sids are connected to one wire. That can be done exactly like the normal SPI test except that there is only one data wire. If we use an XMC4700 board for that, than it should be able to hande both SPI variants.
Something which we haven't yet tried is multiplexing 3wire SPI where the MISO line is not connected and MOSI is doing both directions. BTW. that what they tried with the IMD70xA on the REF36 motorcontroller board.

[Frederikwag]

So we will not merge this test (with the sensor), but develop the "complete" test without the sensor? I would like to keep the ticket until my return in August in order to finish it. Is that ok?