Oppia team updates for 2021 Q3 & Q4

[Jacob Davis]

Dear Oppians

This is the quarterly update on what we've done in Q3 and are working on in Q4. If any of these projects look particularly interesting to you, please get in touch with the team lead to find ways you can contribute. (For project details and contact information see the relevant github project page or ask me.)

Android (Ben)
 - Finish GSoC (6 projects wrapped up), introduced sub-teams to scale team management, and made significant headway on preparing for an upcoming alpha MR3 launch of the app (including finalizing both RTL & support for Arabic & Brazilian Portuguese translations, and introducing various new technical infrastructure).
 - Land Alpha MR3 (i.e. support the upcoming studies), launch Alpha MR4 (requires adding support for algebraic/numeric expression interactions & basic learner analytics), streamline developer onboarding & support, and a variety of UI-related cleanups/reorganizations.

Growth (Isalo)
 - The growth team conducted the first set of Android pilots with partners in Nigeria and Kenya and used the outputs to guide product development and GTM strategy.
 - Develop and launch phase II pilots with partners in Nigeria and Kenya to reach new learners.

Community contribution (Sagang)
 - Introduced a translation contribution stats table for admins and improved the translation suggestion workflow, e.g. not showing numeric content for translation, enabling translation of lesson rules.
 - Fix remaining stability issues and high priority workflow bugs, e.g. better sorting/filtering, email notifications, handling of serious lesson changes.

Speed & stability (Vojtěch)
 - We finished the Python 3 migration and implementation of the most important Beam jobs.
 - Implement more Beam jobs and remove the collections from Oppia.

Angular upgrade (Srijan)
 - Migrated 20 full pages to use angular, router and lazy loading.
 - Migrate the remaining big pages (Exploration editor, topics and skills, etc).

Dev workflow (Sandeep)
 - Moved all the JS/TS regex checks to eslint. Changed oppiaBot structure to support all the necessary workflows for oppia-android project. Refactored and updated the entire oppia/oppia wiki pages. Started caching third_party libs in the CI workflows to reduce each CI build time by 5 mins. Added a notification system for the build failures and fixed multiple e2e test issues to reduce the build flakiness.
 - Complete all the remaining work for the linter team i.e, moving python regex checks to pylint. Complete refactoring the wiki pages and announcing the wiki pages to developers. Adding workflow for sending notification to reviewers if they miss reviewing PRs.

Best wishes

Jacob