oeqa/core: Move OETestContext.log{Summary, Details} into OETestResult

Those methods are used to write in the log the results so
it makes sense to have defined at OETestResult because
is a format of the result itself.

[YOCTO #11450]

(From OE-Core rev: 33a783f59ed4e232f41f8b09dfa7955f2ddc2f80)

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/testimage.bbclass

@@ -292,8 +292,8 @@ def testimage_main(d):
     # Show results (if we have them)
     if not results:
         bb.fatal('%s - FAILED - tests were interrupted during execution' % pn)
-    tc.logSummary(results, pn)
-    tc.logDetails()
+    results.logSummary(pn)
+    results.logDetails()
     if not results.wasSuccessful():
         bb.fatal('%s - FAILED - check the task log and the ssh log' % pn)