Change topLevelPaths option to take a regexp pattern

[rockwotj]

This allows for local imports like ../../resources/styled where the relative path changes so the existing pattern doesn't work.

[quantizor]

@rockwotj can the existing solution support both path types?

[rockwotj]

@probablyup not without breaking the format I think? How else can the string be interpreted as a regex or a literal? Happy to change the existing config option to be an array of objects with a 'type'.

We could also remove the existing config option, regexes are purely more powerful. As a compromise we could also use a library like picomatch to strike a middle ground and then it's also be unlikely we'd break existing patterns that way.

[rockwotj]

Okay @probablyup I've changed this so that the existing pattern now takes a regex. This is a breaking change for anyone that uses the (undocumented) topLevelImportPaths configuration.

[agriffis]

This change resulted in some fallout, see styled-components/styled-components#3635

Regexes are more powerful, but more confusing and prone to error. Either of the other suggestions (picomatch or typed objs) would have been a better approach, and would have avoided the breaking change.

As an example of prone to error, this PR uses re.test which isn't anchored, so now strings in topLevelImportPaths get converted to patterns that match anywhere in the input. The modified test even demonstrates the potential for mistakes:

       "@xstyled/styled-components/*"

This pattern uses * instead of .* but it matches '@xstyled/styled-components/test' anyway because re.test isn't anchored.

@rockwotj @probablyup It seems clear that pinning styled-components to version 1 of babel-plugin-styled-components isn't the best fix, even if it's a temporary workaround for the linked issue. Do you have thoughts on the best path forward?