Request: Possibility to set a custom filename for the barrel files.

[emanuel-lundman]

I know this may be a strange feature request(?), but, the reason is:
In a large package we've started using a custom _barrel.ts filename to be able to more easily find possible circular referenses created accidentally by autoimport in vscode of functions or types from the same library. By using the custom filename we can search for barrel imports locally in the package itself and correct them much more easily, since these imports are often a mistake. The barrels are for external imports from outside of the package not for internal imports within the library package.

So therefor, would be great to be able to choose the names of the barrel files generated.