tests: Extract libusb wraps into separate file

In preparation for adding more tests with lots of libusb wraps,
existing wraps are extracted into separate file.

BUG=b:181803212
TEST=builds and ninja test

Change-Id: I17c1cc0189fcb742a99ad1b0fd615ab95504a74a
Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/57916
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>

tests/meson.build

@@ -16,6 +16,7 @@ root_includes = include_directories('../subprojects')
 srcs = [
   'io_mock.c',
   'tests.c',
+  'libusb_wraps.c',
   'helpers.c',
   'flashrom.c',
   'spi25.c',