Move SyncTelemetryPing to a-c, to fix class resolution errors

[linabutler]

Importing SyncTelemetryPing from a-s doesn't work well with Fenix. 😭 a-c and Fenix build just fine (and the a-c unit tests pass!), but syncing in Fenix throws an java.util.concurrent.ExecutionException: java.lang.NoClassDefFoundError: Failed resolution of: Lmozilla/appservices/sync15/SyncTelemetryPing runtime exception.

Changing Fenix to depend on a-s, and adding sync15 as an api instead of an implementation dependency doesn't work. This takes the hacky (but maybe better, in the long term?) approach of moving SyncTelemetryPing into a-c (mozilla-mobile/android-components#3092), which does work in Fenix.

Pull Request checklist

• Quality: This PR builds and tests run cleanly
  • cargo test --all produces no test failures
  • cargo clippy --all --all-targets --all-features runs without emitting any warnings
  • cargo fmt does not produce any changes to the code
  • ./gradlew ktlint detekt runs without emitting any warnings
  • swiftformat --swiftversion 4 megazords components/*/ios && swiftlint runs without emitting any warnings or producing changes
  • Note: For changes that need extra cross-platform testing, consider adding [ci full] to the PR title.
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry or an explanation of why it does not need one
  • Any breaking changes to Swift or Kotlin binding APIs are noted explicitly
• Dependencies: This PR follows our dependency management guidelines
  • Any new dependencies are accompanied by a summary of the due dilligence applied in selecting them.

[linabutler]

Fixed by mozilla-mobile/fenix#3325.