[Telemetry] Introduce RunState.SetUpBeforeRunPage and RunState.TearDownAfterRunPage.

This is a step closer to the point of making _RunState --> UserStoryState with
the 4 main methods:

__init__ that does classSetUp
SetUpBeforeRunPage that does setUp before each page run
TearDownAfterRunPage that does tearDown after each page run
TearDownAfterRunPageSet that does final classTearDown

BUG=418278

Review URL: https://codereview.chromium.org/692973003

Cr-Commit-Position: refs/heads/master@{#302695}

tools/telemetry/telemetry/page/page_runner_unittest.py

@@ -687,9 +687,9 @@ class RunStateTest(unittest.TestCase):
   # pylint: disable=W0212
   def TestUseLiveSitesFlag(self, options, expected_wpr_mode):
     with tempfile.NamedTemporaryFile() as f:
-      run_state = page_runner._RunState(DummyTest())
+      run_state = page_runner._RunState(DummyTest(), options)
       fake_network_controller = FakeNetworkController()
-      run_state._PrepareWpr(options, fake_network_controller, f.name, None)
+      run_state._PrepareWpr(fake_network_controller, f.name, None)
       self.assertEquals(fake_network_controller.wpr_mode, expected_wpr_mode)
       self.assertEquals(fake_network_controller.archive_path, f.name)