Introduce select operator for Kotlin

[slinkydeveloper]

This makes a bit nicer and more idiomatic the experience with awaitable combinators.

[github-actions]

Unit Test Results

424 tests  +17   414 ✔️ +17   15s ⏱️ -1s
    7 suites ±  0     10 💤 ±  0 
    7 files   ±  0       0 ❌ ±  0 

Results for commit 9a3c2bb. ± Comparison against base commit 77a6d5f.

This pull request removes 216 and adds 233 tests. Note that renamed tests count towards both.

dev.restate.sdk.blocking.JavaBlockingTests ‑ 10: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAll: No completions will suspend
dev.restate.sdk.blocking.JavaBlockingTests ‑ 11: [MockSingleThread][dev.restate.sdk.blocking.DeferredTest] AwaitAll: Only one completion will suspend
dev.restate.sdk.blocking.JavaBlockingTests ‑ 12: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAll: Only one completion will suspend
dev.restate.sdk.blocking.JavaBlockingTests ‑ 13: [MockSingleThread][dev.restate.sdk.blocking.DeferredTest] AwaitAll: Everything completed will generate the combinators message
dev.restate.sdk.blocking.JavaBlockingTests ‑ 14: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAll: Everything completed will generate the combinators message
dev.restate.sdk.blocking.JavaBlockingTests ‑ 15: [MockSingleThread][dev.restate.sdk.blocking.DeferredTest] AwaitAll: Replay the combinator
dev.restate.sdk.blocking.JavaBlockingTests ‑ 16: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAll: Replay the combinator
dev.restate.sdk.blocking.JavaBlockingTests ‑ 17: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAll: Complete all asynchronously
dev.restate.sdk.blocking.JavaBlockingTests ‑ 18: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAll: All fails on first failure
dev.restate.sdk.blocking.JavaBlockingTests ‑ 19: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAll: All fails on second failure
…

dev.restate.sdk.blocking.JavaBlockingTests ‑ 10: [MockSingleThread][dev.restate.sdk.blocking.DeferredTest] AwaitAny: Replay the combinator
dev.restate.sdk.blocking.JavaBlockingTests ‑ 11: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAny: Replay the combinator
dev.restate.sdk.blocking.JavaBlockingTests ‑ 12: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitAny: Complete any asynchronously
dev.restate.sdk.blocking.JavaBlockingTests ‑ 13: [MockSingleThread][dev.restate.sdk.blocking.DeferredTest] ReverseAwaitOrder: None completed
dev.restate.sdk.blocking.JavaBlockingTests ‑ 14: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] ReverseAwaitOrder: None completed
dev.restate.sdk.blocking.JavaBlockingTests ‑ 15: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] ReverseAwaitOrder: A1 and A2 completed later
dev.restate.sdk.blocking.JavaBlockingTests ‑ 16: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] ReverseAwaitOrder: A2 and A1 completed later
dev.restate.sdk.blocking.JavaBlockingTests ‑ 17: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] ReverseAwaitOrder: Only A2 completed
dev.restate.sdk.blocking.JavaBlockingTests ‑ 18: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] ReverseAwaitOrder: Only A1 completed
dev.restate.sdk.blocking.JavaBlockingTests ‑ 19: [MockMultiThreaded][dev.restate.sdk.blocking.DeferredTest] AwaitTwiceTheSameAwaitable
…

This pull request removes 6 skipped tests and adds 6 skipped tests. Note that renamed tests count towards both.

dev.restate.sdk.http.vertx.HttpVertxTests ‑ 118: [HttpVertxTestExecutor][dev.restate.sdk.kotlin.StateTest] Unknown
dev.restate.sdk.http.vertx.HttpVertxTests ‑ 135: [HttpVertxTestExecutor][dev.restate.sdk.kotlin.UserFailuresTest] Unknown
dev.restate.sdk.kotlin.KotlinCoroutinesTests ‑ 109: [MockSingleThread][dev.restate.sdk.kotlin.UserFailuresTest] Unknown
dev.restate.sdk.kotlin.KotlinCoroutinesTests ‑ 110: [MockMultiThreaded][dev.restate.sdk.kotlin.UserFailuresTest] Unknown
dev.restate.sdk.kotlin.KotlinCoroutinesTests ‑ 78: [MockSingleThread][dev.restate.sdk.kotlin.StateTest] Unknown
dev.restate.sdk.kotlin.KotlinCoroutinesTests ‑ 79: [MockMultiThreaded][dev.restate.sdk.kotlin.StateTest] Unknown

dev.restate.sdk.http.vertx.HttpVertxTests ‑ 124: [HttpVertxTestExecutor][dev.restate.sdk.kotlin.StateTest] Unknown
dev.restate.sdk.http.vertx.HttpVertxTests ‑ 141: [HttpVertxTestExecutor][dev.restate.sdk.kotlin.UserFailuresTest] Unknown
dev.restate.sdk.kotlin.KotlinCoroutinesTests ‑ 120: [MockSingleThread][dev.restate.sdk.kotlin.UserFailuresTest] Unknown
dev.restate.sdk.kotlin.KotlinCoroutinesTests ‑ 121: [MockMultiThreaded][dev.restate.sdk.kotlin.UserFailuresTest] Unknown
dev.restate.sdk.kotlin.KotlinCoroutinesTests ‑ 89: [MockSingleThread][dev.restate.sdk.kotlin.StateTest] Unknown
dev.restate.sdk.kotlin.KotlinCoroutinesTests ‑ 90: [MockMultiThreaded][dev.restate.sdk.kotlin.StateTest] Unknown