Add config to specify plugin-transform-react-jsx throwIfNamespace

[CorruptedHeart]

It appears that specifying throwIfNamespace in a .babelrc file no longer causes it to apply to the @babel/plugin-transform-react-jsx or @babel/plugin-transform-react-jsx-development. Even if specifying babelrc: true as a config option.

This is to allow stuff like unocss attributify mode which supports attributes like disabled:bg-grey on elements.

Currently the only documented use case is throwIfNamespace.

[rschristian]

Couldn't you simply specify your own copy of the @babel/plugin-transform-react-jsx plugin with the necessary options?

[CorruptedHeart]

@rschristian due to the order of the spreads here: https://github.com/preactjs/preset-vite/blob/main/src/index.ts#L193-L202, it causes warnings about duplicate plugins.

Also, we'd be relying on the users to also care about stuff like isProduction, etc.

[rschristian]

In that case, perhaps we can detect if the user-provided plugins contains the jsx transform, and if so, replace the plugin config completely (rather than spread into it)?

Another config option is worst-case scenario, and doesn't seem fitting for a niche Babel option.

Also, we'd be relying on the users to also care about stuff like isProduction, etc.

Their config, their choice whether to care or not.