[SAOC 2025] Improve error messages and LSP integration Weekly Update #7

[Iskaban10]

## [SAOC 2025] Improve error messages and LSP integration Weekly 
Update #7

This week I continued working on the PR. [#PR 
21979](https://github.com/dlang/dmd/pull/21979).

I made some more changes to the output of the lsp, especially in 
the format of the JSON array. I have been able to successfully 
add the supplemental messages to their respective error messages 
which I was previously failing to do.
I have also started studying serve-d diagnostics flow. This will 
be required in order to integrate the lsp-diagnostics into 
serve-d which is the lsp server for dlang.