Add FiLM layers to ConvLSTM

[jacobbieker]

Pull Request

Description

Adds the FiLM layers to the ConvLSTM layers for MetNet-2, to better match the paper diagram.

Fixes #31

How Has This Been Tested?

Unit test

• [ ] Yes

Checklist:

• [ ] My code follows OCF's coding style guidelines
• [ ] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have checked my code and corrected any misspellings