Format Selection yields a type loader exception when built with dotnet 7 sdk

[nojaf]

Fantomas.Client and fantomas (tool) are impacted by dotnet/fsharp#14275 when (de)serializing the FormatSelectionRange struct.

While a fix will eventually land in the F# compiler, I suggest we avoid the problem by changing the struct to class.

Both sides would need a new version before the problem would be fully resolved. Users that are not using format selection are not impacted by this.

[auduchinok]

While a fix will eventually land in the F# compiler, I suggest we avoid the problem by changing the struct to class.

@DedSec256 Will that work with Rider integration?

[DedSec256]

@auduchinok, no, since it does not affect Fantomas.Core we are using