Provide an interface for shared paths between Soong and Soong UI.

Code refactoring has been done for logs directory logic code since
the bazel metrics directory depends on the log directory. For builds
that did not specify a dist directory, the log directory is under
out directory. With dist, the logs directory is under <dist dir>/logs.
This matters for Android CI builds where the metrics files are
placed under logs directory. With this change, the bazel metrics
directory and corresponding files will be under <dist dir>/logs
directory for Android CI builds.

Bug: b/174479728
Test: * USE_BAZEL=1 m nothing (bazel_metrics dir in out dir)
      * m nothing (bazel_metrics dir deleted)
      * DIST_DIR=/tmp/build USE_BAZEL=1 m nothing dist (bazel_metrics
        is in /tmp/build/logs directory)

Change-Id: Ic9e1ff49a1964fcaaf801bde2c19f33597ca1db4