Enhance TeamCity Coverage Badge

:clipboard: **Description**

Enhance the TeamCity Coverage Badge to allow the user to specify the coverage metric (lines, statements, etc.) they want to use via a param.

Our current badge implementation is keying off `statement` coverage, but while I was working on resolving https://github.com/badges/shields/issues/2901 I noticed that a lot (actually the majority) of TeamCity projects with coverage did not have `statement` coverage (most had `line` coverage long with `method/function`, and others).

If we allowed the user to specify their target coverage metric (we can still default to `statement`) then we can make the coverage badge for TeamCity available to a much broader set of users

Locate the TeamCity Coverage Badge implementation and inspect how it currently selects statement coverage. Check nearby badge parameter conventions, then add the requested metric selection while preserving statement as the default. Done means TeamCity projects using line or other available coverage metrics can produce the badge, with the existing default still working.

Written by the indexing model from the issue text.