oeqa/selftest/resulttool: add test for metadata filtering on regression

oeqa/selftest/resulttool: add test for metadata filtering on regression

Multiple filters have been added to resulttool to ensure that test
results are compared only to relevant older tests results

Add some unit tests about added filters:
- tests should only be compared when machine matches
- tests run as oeselftest should only be compared when
  OESELFTEST_METADATA matches
- many ptests should match despite non-static names
- runtime tests should match with matching tests regarding ltp tests
  content

Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>