Autoload PostCSS config

[lukeed]

When no options are passed, the @taskr/postcss plugin will now look for & respect configs found within: ~(arranged by preference):~

• a .postcssrc file (JSON-type only)
• the "postcss" key inside package.json
• a postcss.config.js file (Object or Function type)
• a .postcssrc.js file (Object or Function type)

As for usage, all options are available:

// send options (current)
yield task.source(...).postcss({
  plugins: [], 
  options: {}
}).target(...);

// run autoload checks (any of above)
yield task.source(...).postcss().target(...);

An error will be emitted, forcing the plugin to stop, if the final/parsed options is not an Object.

~TODO: Add autoload-config tests.~

Closes #283

[lukeed]

Thanks @hzlmn! Were you able to actually try it out locally, or are you just eyeballing it 👀 😜

[hzlmn]

Both, also I checked it locally with current project, everything works fine. Probably, can just manually test all common configurations... as addition

[lukeed]

No need to do extra checks, unless you really want to. 😄

[hzlmn]

Are there any blockers to merge it? 🤓

[lukeed]

Nope! Going to make some other package changes tonight before pushing a 1.1.0