Fix (mostly) StyleCop warning SA1003 (operator symbol spacing)

Fix (mostly) StyleCop warning SA1003 (operator symbol spacing)

The "mostly" here is that I undid changes where it was forcing formatting around a `: this` or `: base` call for a ctor, in particular where it was moving one up from the next line to be at the end of the current line.

Commit migrated from https://github.com/dotnet/coreclr/commit/f3ca042455a4a1cfa3063b68eeeb698a1201d6f4