* add ::file-selector-button reset
Otherwise you have to apply `file:border-solid` which you don't have to
do for other elements with borders.
See: https://play.tailwindcss.com/EvtdftCPt6
* update changelog
* remove unused `withRule`
* ensure all ::before and ::after elements have content
* update --tw-content for the content plugin
* simplify `before` and `after` variants
* update tests, to reflect changes
* make new `format` and `wrap` API's private for now
* allow returning a format string from `addVariant` callback
* add `content: var(--tw-content)` for before/after variants
* update tests to add `content: var(--tw-content)`
* update changelog
* filter out `..Variant` plugins for the core-plugin-list
* inline all corePlugins
* move preflight css to `./src/css`
* remove individual plugins
* convert export default object to named exports
Note: Normally I would use export function ..., but since we also have
some export let xx = createUtilityPlugin in this file, it means that all
the `export function` declarations would be hoisted and therefore won't
have the correct order anymore.
To fix this, I used `export let xx = () => {}` instead of the usual
`export function xx() {}`
* drop unused `variants()` function
This was required for AOT mode.
* make a few plugins shorter
