Use generic collections in System.ComponentModel.TypeConverter implementation instead of non-generic

[twsouthwick]

[karelz]

Should be fairly simple to do. Anyone wants to pick it up?

[marcusturewicz]

Is this for the entire System.ComponentModel.TypeConverter assembly or just the TypeConverter class from that assembly?

[eerhardt]

Note: not all usages of non-generic collections were replaced, by design. See #63315 (comment) for the reasoning. We replaced the ones that were obvious. But any more conversions here would need to be backed by data showing why the change must happen.