Feat/source maps

[qnp]

Hello,

I have an attempt here to add full source-maps support for this plugin:

• emit source map for templates (inspired by vue 3)
• emit source map for styles
• use empty source map to avoid rollup complaining

Tell me if you think it is correct,

I'm not sure how to debug the built sourcemaps..

Best,

[underfin]

Thanks for your work, but add template block sourmap will conflict with script block sourcemap at hmr, so i revert it. Just use map: null also let rollup happy.

[qnp]

Perfect, thank you.