Fix env setting and Android setup (#1085)

Summary:
*Context: The Yoga OSS build has not been given a lot of attention over the past couple of years and is in serious disrepair. I'll try to get the release pipeline going again to publish to Maven Central as JCenter is shutting down. A bunch of intermediate commits may still have broken builds but will be inching closer to a working one.*

The current way env variables are set is no longer supported for security reasons: https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/. The manual Android setup is also quite tricky to maintain and can mostly be done through GitHub Actions itself.

Please note that the actual build is still failing but that's because we're so far behind with the setup here that the Gradle version no longer works on a modern JVM. I'll fix that in subsequent diffs.

Pull Request resolved: https://github.com/facebook/yoga/pull/1085

Test Plan: CI

Reviewed By: mweststrate

Differential Revision: D28602084

Pulled By: passy

fbshipit-source-id: e334ed92d16a9baa185a84b23bb62801399e5650

.github/workflows/ci.yml

@@ -44,13 +44,8 @@ jobs:
           cd buck
           ant
           popd
-          echo "::set-env name=PATH::$PATH:$HOME/buck/bin/"
+          echo "$HOME/buck/bin" >> $GITHUB_PATH
           export PATH=$PATH:$HOME/buck/bin/
           buck --version
-          export TERMINAL=dumb
-          source scripts/android-setup.sh && installAndroidSDK
-          echo "::set-env name=ANDROID_SDK::$ANDROID_HOME"
-          echo "::set-env name=ANDROID_NDK_REPOSITORY::$HOME/android-ndk"
-          echo "::set-env name=ANDROID_NDK_HOME::$ANDROID_NDK_REPOSITORY/android-ndk-r15c"
       - name: Build
         run: ./gradlew testDebugUnit && scripts/publish-snapshot.sh