DataProtectionProvider should expose a Create method which only takes setupAction

## Background and Motivation

Today, `DataProtectionProvider` offers a number of different `Create` factory methods. All of them take either an application name or a key directory, along with a few other parameters.

However, it is possible to use data protection without storing keys on the file system. This is doable with the API today via the setup action parameter, but it is awkward because you still have to pass a key directory which is not used. For example:

```
var provider = DataProtectionProvider.Create(
new DirectoryInfo(@"X:\fake\directory"), // ignored
b =>
{
b.SetApplicationName("APTPlatform");
b.Services.AddSingleton>(services =>
{
return new ConfigureOptions(o =>
{
o.XmlRepository = new MyRepository();
...
});
});
});
```

## Proposed API

```
namespace Microsoft.AspNetCore.DataProtection;

public static class DataProtectionProvider
{
+ public static IDataProtectionProvider Create(Action setupAction);
}
```

## Usage Examples

```
var provider = DataProtectionProvider.Create(
b => b.SetApplicationName(...).PersistKeysTo...().ProtectKeysWith...()
);
```

## Alternative Designs

Rather than requiring _only_ setupAction, we could offer a creation method with application name + setup action. I'm not sure why the current set of create methods were designed the way they were (e.g. why do we think users will either know the key directory or the application name?).

## Risks

The risk seems low, since you can effectively do this today by just overriding the key persistence in your setup action. However, it would make the code a bit easier to understand.