Update transifex api from v2 to v3

[Mashal-m]

Ticket Updating /api/v2 transifex endpoints

What has changed?

• Update Makefile commands for new v3 transifex API
• Add edx/reactifex as dependency

Reference PR https://github.com/openedx/frontend-app-learning/pull/837

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (07eb589) 81.25% compared to head (9861a15) 81.25%.

:exclamation: Current head 9861a15 differs from pull request most recent head 9292cdc. Consider uploading reports for the commit 9292cdc to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #272 +/- ## ======================================= Coverage 81.25% 81.25% ======================================= Files 4 4 Lines 32 32 Branches 4 4 ======================================= Hits 26 26 Misses 6 6 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openedx). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openedx)

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