feat: Add IterableAsyncQueue.

[kinyoklion]

BEGIN_COMMIT_OVERRIDE
feat: Add IterableAsyncQueue.
feat: Update minimum Java version to 1.8.
END_COMMIT_OVERRIDE

---

Note

Medium Risk
Raising shared/common’s Java baseline to 1.8 can break consumers pinned to Java 7; the new queue is well-tested but adds new concurrency code paths.

Overview
Adds com.launchdarkly.sdk.collections.IterableAsyncQueue, a thread-safe unbounded FIFO queue whose take() returns a CompletableFuture that completes immediately when items exist or later when put() supplies one, plus package docs.

Updates lib/shared/common to target Java 8 (1.8) and adds an extensive JUnit test suite covering ordering, null handling, and multi-threaded producer/consumer behavior.

^{Written by Cursor Bugbot for commit e78dcde. This will update automatically on new commits. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.}