Update V14 > V23 upgrade guide after 23.2 release

[tarekoraby]

V14 > V23 upgrade guide should be updated to reflect changes introduced by the release of V23.2.

[rolfsmeds]

Minor breaking changes in components:

• ~https://github.com/vaadin/web-components/pull/4272 : Custom styling of <h2> elements may affect Dialog's title, which is now a slotted <h2> element. Workaround: Override h2 styling specifically for Dialog (css: vaadin-dialog-overlay > h2 { ...}) or exclude dialog titles from your h2 styles (css: *:not(vaadin-dialog-overlay) h2 {...} )~ (Edit: This should not affect migrators from V14 as the title element did not even exist in V14.)
• [x] https://github.com/vaadin/web-components/pull/4149 : Lit: Checkbox Group's value property is now immutable.
• [x] https://github.com/vaadin/web-components/pull/4095 : Lit: Number Field no longer has a default step value.
• ~https://github.com/vaadin/web-components/pull/3944 : Lit: Changes to ComboBox internal (non-visible) DOM structure may affect custom extensions of the component.~(Edit: not really meaningful to list in V14 migration docs as the component's entire DOM has changed so fundamentally compared to V14.)

Edit: the remaining 2 issues are now covered in https://github.com/vaadin/docs/pull/1688

[mshabarov]

Breaking changes in Flow 23.2:

• [ ] https://github.com/vaadin/platform/issues/3009 : Vite is now used by default for bundling the frontend resources and running the dev server. Thus, if your project has a custom configuration for Webpack in webpack.config.js, it should be adapted to the Vite configuration, otherwise, you can still use Webpack through a feature flag.
• [ ] https://github.com/vaadin/hilla/issues/208 : Hilla endpoint classes were moved to Hilla repository from Flow.
• [ ] https://github.com/vaadin/flow/issues/13769 : in non-Spring based Vaadin application, if a custom servlet mapping is used, one should add /VAADIN/* to the url patterns of the custom Vaadin servlet.
• [ ] https://github.com/vaadin/flow/pull/13679 : DevModeGizmo renamed to DevTools. This affects configuration parameter name (devmodeGizmoEnabled -> devToolsEnabled) and method name in DeploymentConfiguration.
• [ ] https://github.com/vaadin/flow/issues/14143 : one can use RouterLink without text parameter now. But if you were using new RouteLink(null, MyView.class), you have to replace it with new RouterLink(MyView.class), otherwise you get compilation error.
• [ ] https://github.com/vaadin/flow/pull/14324 : The new license checker is triggered also for production builds and requires an offline license for development in an offline environment.