Docgen: parse constructorName from AST

[layershifter]

Feature Request

We need try to replace this with parsing the AST that is provided in getComponentInfo().

Problem description

https://github.com/stardust-ui/react/blob/v0.14.0/build/gulp/plugins/util/getComponentInfo.ts#L45
This require() will cause the TS transpilation of all included files, this slowdowns our build in CI for 20 seconds. Local builds are slowed down, too.