faces: Add SuffixSpinBox as spinbox control with read-only suffix
- faces: Use SuffixSpinBox in pie and line chart config pages
- faces: Add SuffixSpinBox as spinbox control with read-only suffix
This is intended to replace spinboxes with suffixes that are part of the text, which causes issues when editing values. Instead, this has the suffix as a separate label item that is not part of the value at all.