[SAoC2022] Replace libdparse with dmd-as-a-library in D-Scanner

[Lucian Danescu]

Hello!

Since the last update I created PRs for the following visitors:
- 
[redundant_attributes](https://github.com/Dlang-UPB/D-scanner/pull/29)
- 
[label_var_same_name](https://github.com/Dlang-UPB/D-scanner/pull/30)
- [local_imports](https://github.com/Dlang-UPB/D-scanner/pull/31)

PS: The above pr's will be closed because I messed the history 
and while trying to rebase
I need to fix a huge number of conflicts :), will probably just 
create new pr's with the
same changes. Also I did some refactoring for other pr's that I 
opened in the past applying
my mentor's suggestions, and for now I will focus on getting the 
active pr's right and mergeing
them so I and other people checking out the repository won't get 
confused by the number of pr's

Also while working on a separate visitor I stumbled upon a 
potential issue, regarding the location
of `AliasDeclaration`, so I created this 
[pr](https://github.com/dlang/dmd/pull/14602) that needs
more work but feel free to take a look and leave a comment if you 
have any suggestions.

Thank you!