feat: run Vaadin plugin as build step

[mcollovati]

Embeds the logic of Vaadin prepare-frontend and build-frontend tasks into a build step to allow project to run without configuring Vaadin Maven and Gradle plugins.

Fixes #64

[quarkus-hilla-bot]

Format Checker Report

All files are correctly formatted

[github-actions]

Test Results

 45 files   - 22   45 suites   - 22   11m 1s ⏱️ - 1m 45s
188 tests  - 28  187 ✅  - 28  1 💤 ±0  0 ❌ ±0 
239 runs   - 77  238 ✅  - 77  1 💤 ±0  0 ❌ ±0 

Results for commit 1920e10. ± Comparison against base commit 0a61697.

This pull request removes 28 tests.

com.example.application.AutoCrudTest(production) ‑ autocrud_gridAndFormDisplayed
com.example.application.AutoCrudTest(production) ‑ autocrud_newUser_userSaved
com.example.application.AutoCrudTest(production) ‑ selectUser_delete
com.example.application.AutoCrudTest(production) ‑ selectUser_editAndDiscard
com.example.application.AutoCrudTest(production) ‑ selectUser_editAndSubmit
com.example.application.AutoFormTest(production) ‑ loadUser_editAndDiscard
com.example.application.AutoFormTest(production) ‑ loadUser_editAndSubmit
com.example.application.AutoFormTest(production) ‑ newUser_userSaved
com.example.application.AutoGridTest(production) ‑ autoGrid_filter
com.example.application.AutoGridTest(production) ‑ autoGrid_gridIsDisplayed
…

♻️ This comment has been updated with latest results.