Add slnx file migrated from sln

[thegu5]

Both VS and (recently) Rider support the format.

If this is merged now, the .sln file will still have to be relied upon and kept in sync if any changes are made to the .slnx file, since the new format isn't supported everywhere yet. The biggest example is the dotnet CLI, which has release of the feature planned for 9.0 (dotnet/sdk#40913). Rider has a feature to convert between the two.

(Due to the above, maybe hold off on merging?)

🎃

[coveralls]

Pull Request Test Coverage Report for Build 19786088216

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 34.31%

---

Totals
Change from base Build 18333364266:	0.0%
Covered Lines:	4191
Relevant Lines:	10847

---

💛 - Coveralls

[ds5678]

@thegu5 Can you rebase?

[thegu5]

Fixing...

[thegu5]

Everything looks good now, I removed the original sln file since the project is built with dotnet 9 now