Consider adding TryParse() methods to every AsX method in FieldValue and DocumentField

[maririos]

Feedback from our customers where when trying our AsX where X is a type methods in FieldValue and DocumentField we throw exception when the Type doesn't match.
It will be more convenient to have a TryParse method that the user can call that will return a bool value.
See https://docs.microsoft.com/en-us/dotnet/standard/design-guidelines/exceptions-and-performance#try-parse-pattern

[maririos]

We need to understand which scenarios are causing the throwing and if the if ( xx is type chu) is enough or not

[maririos]

Moving to backlog while working on the design. According to when it is ready and approved will add to an active milestone

[kinelski]

After discussing this matter with architects, we won't implement AsX methods as it could just make the class more confusing to customers.

We decided to add an DocumentFieldType.Unknown enum value that can be used in these scenarios. More information here: #30909

Updated the way DocumentField is handled. When the field value is not returned by the service (which happens when they can't parse the extracted value into the expected type), we set DocumentField.FieldType to DocumentFieldType.Unknown in the SDK. Customers could then use the DocumentField.ExpectedFieldType in addition to the raw string DocumentField.Content to manually parse the field value in this case. This change permits handling this scenario without try/catch blocks (current approach).