feat: auto-configure virtual threads for SQS listener containers

[Theprathamshah]

📢 Type of change

• Enhancement

📜 Description

This pull request adds native support for Java 21+ Virtual Threads to SQS listener container factories.

• Modifies SqsAutoConfiguration to detect the standard Spring Boot property spring.threads.virtual.enabled.
• When enabled, configures SimpleAsyncTaskExecutor (with virtualThreads = true) for both the message processing executor (componentsTaskExecutor) and the acknowledgment executor (acknowledgementResultTaskExecutor).

💡 Motivation and Context

Closes #1693.
Integrates Spring Boot's global standard spring.threads.virtual.enabled toggle directly into Spring Cloud AWS SQS listeners, allowing users to leverage high-throughput non-blocking concurrency (Project Loom) out-of-the-box on Java 21+ stacks.

💚 How did you test it?

1. Added unit tests in SqsAutoConfigurationTest verifying SQS containers operate on virtual threads when enabled and fallback to standard platform thread execution when disabled.
2. Verified all tests compile and pass successfully.

[tomazfernandes]

@Theprathamshah , thanks for the PR.

Let's keep this PR scoped to SQS, and please open a separate one for Kinesis and other integrations.

[Theprathamshah]

@tomazfernandes Sure let me create separate PR for kinesis.

[Theprathamshah]

@tomazfernandes I've separated the changes as discussed. This PR focuses exclusively on the SQS listener container auto-configuration (the Kinesis changes are in #1696).

Both are ready for review whenever you have time. Thanks!

[Theprathamshah]

Hi @tomazfernandes @MatejNedic ,just following up to see if you have any feedback or suggestions on this PR when you get a moment.

Also, could you please approve the CI workflow when convenient so we can ensure the automated checks pass? Thanks!

[tomazfernandes]

@Theprathamshah I approved the CI workflow for this PR. There seems to be some failing tests, please take a look.

[Theprathamshah]

Hi @tomazfernandes, thanks for pointing that out! I've updated the tests to use reflection for isVirtual() and added @EnabledForJreRange(min = JRE.JAVA_21) so they compile and run cleanly across the entire JDK 17 / 21 / 24 matrix.