Make System.String interactive

[rpetrusha]

Make System.String interactive

System.String is a high page-view reference topic in reference hub format; that is, it contains encyclopedic documentation for the String class, along with numerous examples.

[SpaceShot]

I'm looking at the rest of the examples. The examples using System.IO do not work in try.dot.net (I believe this is a security consideration, at least for now).

Many of the cultural comparisons give different results than the results expected in the trailing comments in try.dot.net. In some cases it was clear to me the try.dot.net result wasn't correct. So I began double-checking them against the same sample running in .NET Core 2.2. Simple console apps matched the output from the trailing comments.

In the end, I decided that there may be something wrong with cultural comparison in try.dot.net and I decided not to convert any of those samples (samples that use System.Globalization), even if their results matched the trailing comments (i.e. they "seemed to work"). This could be by luck, and someone who decides to play with the sample might get confused later.

Beyond that, I am looking at the remaining samples to propose a PR to change the simplest conversions over to try.dot.net interactive.

[mairaw]

Thanks @SpaceShot. We have reported some issues with code that relies on culture information at dotnet/try#168.

And yes, System.IO not working in Try .NET is by design.

[rpetrusha]

System.Strinng is currently interactive.