[skip-ci] initial support for stream installs, add ftp installs.

do NOT build or release binaries of this version, it is not complete and there will be dragons.

sphaira/include/yati/source/base.hpp

@@ -10,6 +10,10 @@ struct Base {
     // virtual Result Read(void* buf, s64 off, s64 size, u64* bytes_read) = 0;
     virtual Result Read(void* buf, s64 off, s64 size, u64* bytes_read) = 0;
 
+    virtual bool IsStream() const {
+        return false;
+    }
+
     Result GetOpenResult() const {
         return m_open_result;
     }