Expose Error Parser / standalone usage of filter

I want to use the error parser because I want to show the code frame. To skip packages which are filtered too It were nice there would be a way to use the applied filters on an own parsed error.

No files, tests, or entry points are named. Start by locating the error parser and the implementation of the applied filters, then determine how both can be used independently. Done means callers can obtain a code frame and apply the existing filters to an independently parsed error.

Written by the indexing model from the issue text.