Added ru-RU locale

<!-- Try not to make duplicates. Do a quick search before posting LANGUAGES NOTE: Please check https://developers.google.com/assistant/sdk/reference/rpc/languages to check if the language you are adding is supported. --> ### Description PR that adds a Russian localisation to Assistant app itself. ### Resolved / Related Issues Issues resolved or addressed by this PR. - Addresses #488 ### Type of Change - [ x ] Localization P.S. I have no ways to build the assistant on my Windows laptop, tho I don't think a locale would break something important, huh.