…x HTML file for application builder

The generated HTML files for the application were previously not included in the hash calculations for
the service worker. This has now been corrected and the index file for an application will not be included
when service worker support is enabled via the `serviceWorker` option.

(cherry picked from commit c0db618)

…css when needed

Prior to this change a postcss instance was created for every component style. This can cause a performance overhead when using tailwindcss, since each tailwind instance would do multiple IO calls to get the list of files specified in the `content` field.

(cherry picked from commit 48b2732)

…on Windows with application builder

When using the `application` or `browser-esbuild` builder in watch mode on Windows, the project root
will now be watched by default. This provides a workaround for users of Visual Studio which uses a
file save mechanism that causes the watch mode to not correctly trigger. By watching the entire
project root, this problem is avoided. However, this may result in additional rebuilds due to changes
of unrelated files in the project root.
This behavior can be disabled using the environment variable `NG_BUILD_WATCH_ROOT=0`. On non-Windows
platforms, disabled is the default.

Addresses #26437

(cherry picked from commit 96b5b10)