TargetFile validation on Extract

[dzsquared]

• SqlPackage or DacFx Version: SqlPackage 19.1
• .NET Framework (Windows-only) or .NET Core: .net core
• Environment (local platform and source/target platforms):

Steps to Reproduce:

1. Extract a database with the extracttarget property set to anything other than the default (dacpac), set the target file to either a folder path or a *.sql file
2. Receive an error that the target file isn't a .dacpac The TargetFile argument must refer to a file with a '.dacpac' extension.

(new error related to the addition of /p:ExtractTarget)