Allow the native pointer to be stolen

[Xpl0itR]

That is, the NativeMemoryArray is no longer the "owner" of the pointer and it is now the responsibility of the caller to free the memory.

Real life example:

public unsafe int LoadFromBuffer(NativeMemoryArray<byte> buffer, string schema = "main") =>
    SQLitePCL.raw.sqlite3_deserialize(
        SqliteConnection.Handle,
        schema,
        (nint)buffer.StealPointer(),
        buffer.Length,
        buffer.Length,
        raw.SQLITE_DESERIALIZE_FREEONCLOSE | raw.SQLITE_DESERIALIZE_RESIZEABLE);

[Xpl0itR]

If we would prefer to not add another field, we could replace isDisposed and isStolen with something like canDispose.

[neuecc]

Thank you, I think it's good.
I'll release it!