Change in flashrom[master]: tests: Add unit test to run init/shutdown for dummyflasher.c

[Edward O'Callaghan (Code Review)]

Attention is currently required from: Nico Huber, Angel Pons, Anastasia Klimchuk.
Edward O'Callaghan has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/52497 )

Change subject: tests: Add unit test to run init/shutdown for dummyflasher.c
......................................................................

Patch Set 2:

(3 comments)

Commit Message:

https://review.coreboot.org/c/flashrom/+/52497/comment/da71e440_574114d0 
PS2, Line 9: I plan to do this for all drivers in programmer table,
           : one at a time. Dummy is the first and it does not need
           : mocks.
           : 
This explains a overarching strategy however is spare on the detail of the commit itself.

May I recommend something along the lines of;

```
"
Introduce test to exercise that init and teardown of drivers correctly manage the drivers life-time state. We constrain ourselves to dummyflasher in particular here as it does not need any mocking.
"
```

https://review.coreboot.org/c/flashrom/+/52497/comment/a42a2a1a_3a233fdf 
PS2, Line 13: After this was rebased on the top of memory checks
            : https://review.coreboot.org/c/flashrom/+/51243 ,
            : dummy has been discovered to leak memory on shutdown,
            : so I fix it here.
separate patch as it is not related to the introduction of the test code itself just that a previously introduced test found a bug.

File dummyflasher.c:

https://review.coreboot.org/c/flashrom/+/52497/comment/060d6f22_432457ff 
PS2, Line 653: free(data);
Fix the memory leak in a separate patch as not to be conflated with the introduction of test code. The fix stands upon it's own merit.