X500DistinguishedName cannot parse an unquoted name

### Description

When using the constructor of `X500DistinguishedName` and passing in an unquoted RDN, an exception is thrown. This is despite the `X500DistinguishedNameFlags.DoNotUseQuotes` flag being used.

This is despite unquoted (but correctly escaped) DNs being allowed according to the RFC1779.

FIrst reported on [StackOverflow](https://stackoverflow.com/questions/79910134/x500distinguishedname-doesnt-work-with-escaped-commas).

### Reproduction Steps

We can show it doesn't even parse back its own output.
```cs
var dn = new X500DistinguishedName("CN=\"Litware\\, Adatum\",DC=Fabrikam,DC=COM");
var decoded = dn.Decode(X500DistinguishedNameFlags.DoNotUseQuotes | X500DistinguishedNameFlags.Reversed);
var dn2 = new X500DistinguishedName(decoded, X500DistinguishedNameFlags.DoNotUseQuotes | X500DistinguishedNameFlags.Reversed);
```

### Expected behavior

The DN should be parsed, without any string pre-manipulation of the input.

### Actual behavior

`CryptographicException`
```
The string contains an invalid X500 name attribute key, oid, value or delimiter.

at System.Security.Cryptography.X509Certificates.X509Pal.X500DistinguishedNameEncode(String distinguishedName, X500DistinguishedNameFlags flag)
at System.Security.Cryptography.X509Certificates.X500DistinguishedName..ctor(String distinguishedName, X500DistinguishedNameFlags flag)
```

### Regression?

_No response_

### Known Workarounds

Obviously you can just make sure to get the DN quoted, but sometimes inputs come from elsewhere, and regexing them probably isn't wise.

### Configuration

.NET 9.0.14
Windows 11 25H2 26200.8037

### Other information

It appears to be calling through to the `CertStrToNameW` function in WINAPI, which in turn is not able to parse this despite the correct flag being thrown.