New Issue: Get started with new chpldoc implementation

18506, "aconsroe-hpe", "Get started with new chpldoc implementation", "2021-10-01T15:40:32Z"

Goal: parse a (simple) module and generate an rst file

[ ] Check out and become familiar with the existing chpldoc
[ ] Set up a new CMake target for the new chpldoc
[ ] Learn about uAST and dump them
[ ] Generate rst for simple examples

Links to #2525

Example goal:

/* this is the docs string to put in the generated rst file */
module M { }


Module M