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

[Lucian Danescu]

Hello!
​
Since my last update I implemented the following checks using 
`dmd-as-a-library`:
  - 
[redundant_storage_class](https://github.com/Dlang-UPB/D-scanner/pull/60)
  - 
[redundant_parens](https://github.com/Dlang-UPB/D-scanner/pull/61)
  - [useless_asert](https://github.com/Dlang-UPB/D-scanner/pull/63)
  - 
[style_guidelines](https://github.com/Dlang-UPB/D-scanner/pull/64)

I also experimented with a "custom lexer" implementation, that's 
the actual `dmd` lexer
but with the posibility to store all the tokens the lexer would 
produce. I think this could
be interesting for other projects as well and you can check out 
my implementation 
[here](https://github.com/Dlang-UPB/D-scanner/pull/62)

I also create this [pr](https://github.com/dlang/dmd/pull/14720) 
in `dmd` fixing a `Location` issue for `StorageClassDeclaration`.

Now as a small drawback I ran into the following situation: The 
`dmd` parser is actually a template that can use different AST 
families,
namely `ASTCodegen` or `ASTBase`. Well there are situations where 
a class from `ASTCodegen` has it's constructor modified. That 
would imply
that the coresponding class from `ASTBase` should implement the 
same constructor, but since `ASTBase` isn't really used anywhere 
in `dmd`
this aspect is pretty easy to miss. This was a bit tricky to me 
because I was not able to run the `dub` tests (because for `dub` 
we are
currently using the `master` `dmd` version, not a numbered one) 
and I was also confused by the fact that the `makefile` would 
work normally
(because in that case we use a specific `dmd` version).

I got that sorted out but still I need to add the modifications 
from `ASTCodegen` in `ASTBase` as soon as possible, and that will 
be my focus
going forward, as this is a blocker because at the moment all 
integration tests using `dub` would fail.

Thank you and happy holidays everybody!