[SAOC 2023] dfmt rewrite - Weekly update #8

[Prajwal S N]

Hi all,

As the second milestone comes to an end, I am very happy to share 
that dfmt+DMD is now many steps closer to being a complete 
feature-rich formatter!

- The AST walk works without any hitches, and the original source 
code is largely reproduced without problems. I've been testing it 
and ironing out the bugs to ensure no code disappears during 
formatting.
- Four of the original transformations provided by dfmt 
(`dfmt_space_before_function_parameters`, 
`dfmt_space_after_cast`, `dfmt_align_switch_statements`, 
`dfmt_space_before_aa_colon`), have now been implemented in the 
new formatter

It is incredibly satisfying to watch it work :) Across the next 
milestone, I'll be working on adding the remaining 
transformations, and ensuring the existing tests pass.