[2.3] Manager Theme Fixes

Fixes misaligned confirm icons/message, see https://github.com/modxcms/revolution/pull/11697 and https://github.com/modxcms/revolution/issues/11696  too (but my correction also takes windows with no icon into account)

- Fixes package manager breadcrumb looking crappy in FF
- Fixes buttons in Firefox (cut off, too big etc.)
- Fixes outline issue in Firefox on the multiselect options close button
- Fixes the red loading mask text everywhere, see #11695 too
- Fixes unnecessary scrollbars in windows (on Windows OS)