DSL Compiler Redesign

[walterddr]

See:
https://docs.google.com/document/d/1B0O9FbfwC_XDjoB2mL8Dtmv8VeRxhkGX7090dZGbhJ4/edit#

New compiler needs to be flexible enough to handle different DSLs, but should be clean in terms of how to compiler vertex and job graph

1. vertex should be compiled via incoming edge and component definition only (Rule-base Compilation Pattern #17)
2. any additional transformation needed is done via downstream vertex (e.g. keyby, repartition, etc)
3. support reference -> this can either be done in DSL redesign #13 or here.
   [BONUS]. components stored intermediately during compilation in each vertex (e.g. the DataStream coming all the way from source until current) is stored in a more generic manner

Optionally,
Code-Restructure: create a flux-level compilation graph generator in flux-core and remove it from the flink-flux compilation core level (Under discussion whether it should fit in #14 or here)