Deprecate metric executable_lines_data and expose a clean Sensor API as a replacement

When executable_lines were introduced, we decided to use a metric to let Sensor provide the value. This is not optimal since the information is only used during analysis to compute coverage. Storing the measure is a waste of space.
Unfortunately, we can't directly stop saving it since some users might rely on it (or integration tests). So we should deprecate it, and introduce a clean API (like for coverage) as a replacement.