Allow more customisation of rollup configuration

Is your feature request related to a problem? Please describe. I’m using vite to build a site with Svelte, using Svite. It works well! The only missing link for me is supporting older browsers. It’d be ideal to have a way to run babel over the code, just before minification.

Describe the solution you’d like If I manually modify the rollup config builder to inject the @rollup/plugin-babel plugin, it works well. Ideally I’d like a way to do that via configuration - it’s already possible to add plugins before other plugins, but it would be good to have more fine-grained control over their insertion order in the config.

Describe alternatives you’ve considered Not supporting around 5% of my userbase, unfortunately.

[zhangyuang]

@Fanna1119 you can use config.rollupOutputOptions cover default output file name

[underfin]

it’s already possible to add plugins before other plugins, but it would be good to have more fine-grained control over their insertion order in the config.

@antony As you said that be more better, but it is not feasible by the common way contorl it, it will caused many complexity.I just close it for the clear issues, we can keep discuss this if anyone have a good idea to implement it.