fix: forward messages asynchronously in Vite websocket proxy

[mcollovati]

Description

Prevents deadlocks in Quarkus environments.

Fixes #15744

Type of change

• Bugfix
• Feature

Checklist

• I have read the contribution guide: https://vaadin.com/docs/latest/guide/contributing/overview/
• I have added a description following the guideline.
• The issue is created in the corresponding repository and I have referenced it.
• I have added tests to ensure my change is effective and works as intended.
• New and existing tests are passing locally with my change.
• I have performed self-review and corrected misspellings.

Additional for Feature type of change

• Enhancement / new feature was discussed in a corresponding GitHub issue and Acceptance Criteria were created.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

No Coverage information
0.0% Duplication

[github-actions]

Test Results

   940 files  ±  0     940 suites  ±0   54m 29s ⏱️ +46s
5 887 tests ±  0  5 852 ✔️ ±  0  35 💤 ±0  0 ❌ ±0 
6 139 runs  +11  6 097 ✔️ +11  42 💤 ±0  0 ❌ ±0 

Results for commit bf6ebe9. ± Comparison against base commit 3951cce.

[vaadin-bot]

This ticket/PR has been released with Vaadin 24.0.0.alpha10 and is also targeting the upcoming stable 24.0.0 version.