Add a new DAE pass with a fixed point analysis

[tlively]

DAE can be slow because it performs several rounds of interleaved
analysis and optimization. On top of this, the analysis it performs is
not as precise as it could be because it never removes parameters from
referenced functions and it cannot optimize unused parameters or results
that are forwarded through recursive cycles.

Start improving both the performance and the power of DAE by creating a
new pass, called DAE2 for now. DAE2 performs a single parallel walk of
the module to collect information with which it performs a fixed point
analysis to find unused parameters, then does a single parallel walk of
the module to optimize based on this analysis.

[tlively]

This replaces #8085 because so much has changed in the meantime.