Reviewed by Eric Seidel.

        Move more SheriffBot smarts into FailureMap
        https://bugs.webkit.org/show_bug.cgi?id=46703

        This patch pushes the FailureMap model object further into the
        SheriffBot machine.  In addition, it moves a couple operations on this
        object from SheriffBot itself to the model.

        Eventually, FailureMap will be the canonical context object for
        SheriffBot operations.  FailureMap represents a map of the current
        failures on the bots that might require remediation.

        * Scripts/webkitpy/common/net/failuremap.py:
        * Scripts/webkitpy/common/net/regressionwindow.py:
        * Scripts/webkitpy/tool/commands/queries.py:
        * Scripts/webkitpy/tool/commands/sheriffbot.py:
        * Scripts/webkitpy/tool/mocktool.py:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@68740 268f45cc-cd09-0410-ab3c-d52691b4dbfc