[Feature] report build time in build mode

[sun0day]

description

It would be helpful to optimize vite plugins and config if vite can show total build time after building, especially for plugin development and some monolith projects. There are 3 sub-features I think:

• show total build time after all bundles end
• show build time of each bundle
• expose build time metrics via vite.build(...) API

related PR

#12100

[chenxch]

goog idea~