[postcss-custom-properties] : replacement focussed on `importFrom` / `exportTo`

[romainmenke]

see : #527

• importFrom and exportTo have been removed from this plugin.
• a new plugin needs to be created to replace it.
• this new plugin would only do importFrom / exportTo

Although we have the design tokens plugin it is not a drop in replacement and has a much smaller scope. Providing a drop in replacement will cause less issues for users.

[romainmenke]

I am considering not creating/shipping a drop in replacement.
Main reason not to, would be to save us some bandwidth.
I don't really want to poor time and effort into these as I personally view it as a dead end.

• users can pin the current version of the plugin and keep using that for the next couple of years
• users can temporarily switch to non-dynamic imports/exports of this data
• users can migrate to a successor plugin
• users can ask for new features in one of the successor plugins
• anyone is free to take the old plugins and continue maintaining them.

@Antonio-Laguna do you have thoughts about this?

[romainmenke]

The drop-in replacements have been created but we will not be releasing this.
We have decided against taking on maintenance for these plugins.

Anyone is free to take the source code for these replacement plugins and release them as their own!

#734

[romainmenke]

PostCSS JIT props is also an interesting replacement : https://github.com/GoogleChromeLabs/postcss-jit-props