Provide support for Python io - Core tools for working with streams

**Is your feature request related to a problem? Please describe.**
Python 3.8 is used in our project. We are using serverless functions in our project and therefore the data (STL files) we want to process arrives as a bytestream. If we want to load the stl data, we need to first store it somewhere locally only to load it then again with opend3d, since we only can pass in a path + file as string. Therefore it would be really nice to fully support the Python io module: https://docs.python.org/3/library/io.html

**Describe the solution you'd like**
It would be nice if we could just pass a file handle to the read and write functions instead of / in addition to passing in a filename

**Describe alternatives you've considered**
I am still searching for an alternative.