localrepo: use _manifestmatches instead of duplicating logic

basectx: add _manifestmatches method This method is a duplicate of localrepo.mfmatches and sets the stage for factoring localrepo.status into a context method that will be customizable based on inheritance and object type.

localrepo: always set the variable r in status method This is a small patch to help streamline keeping tracking of the list of files for status in a variable already called 'r' ('s' is for subrepos in this method). We now move the setting of it out of an 'if' block so that we can later refactor more code into the context objects.

run-tests: execute tests via unittest Now that unittest mode is functionally equivalent to the default mode, we switch the default execution mode to unittest and remove the choice of different execution modes.

run-tests: implement Test.__str__ unittest sometimes does a str(test) and the default implementation doesn't do the right thing. So we override it.

run-tests: make failure reporting in unittest mode equivalent to default Unlike unittest's defaults, our result formatter does not print stack traces. Here, we change TestResult.addFailure() to be compatible with the existing/default execution mode.

run-tests: ignore failures from rmtree rmtree() may fail under certain conditions. We ignore failures at the individual test level because they can interfere with test execution. Furthermore, we'll reattempt deletion in the high-level test runner after all tests have finished. Note that this patch is not a code refactor like most of the patches before it. This change logically makes sense given the execution behavior of the tests.

run-tests: abort tests after first failure in unittest mode There is an execution mode on run-tests.py that stops after the first failure. unittest mode was previously not obeying this option. This patch fixes that.

run-tests: print compatible output from TextTestRunner Our unittest TextTestRunner now prints output similar to the output from the default execution mode - the output people expect from run-tests.py.

run-tests: don't print results in unittest mode A subsequent patch will have unittest print tests for us. Don't perform old-style printing when in unittest mode.