[2.3] [Re-build] Manager Theme: Fix labels / tvs in custom FC tabs

This PR addresses https://github.com/modxcms/revolution/issues/11758 and creates a (consistent) form with labels on top for custom FC tabs, had to change the way the tv specific padding left is applied because of the tv reload button (was fixed for the standard tvs-wrapper, but not applied for custom tabs)

looks now like that:
![bildschirmfoto 2014-07-21 um 16 54 51](https://cloud.githubusercontent.com/assets/445501/3645080/02601230-10e7-11e4-9721-a596181ee511.png)