Fix constraint issues

[michalrentka]

• Fix autolayout constraint issues in PDF controller:

(
    "<NSAutoresizingMaskLayoutConstraint:0x281556f30 h=--& v=--& _UIToolbarContentView:0x1483bad40.height == 0   (active)>",
    "<NSLayoutConstraint:0x281751ae0 V:|-(0)-[_UIButtonBarStackView:0x1483bb0e0]   (active, names: '|':_UIToolbarContentView:0x1483bad40 )>",
    "<NSLayoutConstraint:0x281751cc0 _UIButtonBarStackView:0x1483bb0e0.bottom == _UIToolbarContentView:0x1483bad40.bottom   (active)>",
    "<NSLayoutConstraint:0x2815577a0 UIButtonLabel:0x14c547130.centerY == _UIModernBarButton:0x14c546d00'Select'.centerY + 0.5   (active)>",
    "<NSLayoutConstraint:0x281568500 'TB_Baseline_Baseline' _UIModernBarButton:0x14c546d00'Select'.lastBaseline == UILayoutGuide:0x280fc07e0'UIViewLayoutMarginsGuide'.bottom   (active)>",
    "<NSLayoutConstraint:0x281568fa0 'TB_Top_Top' V:|-(>=0)-[_UIModernBarButton:0x14c546d00'Select']   (active, names: '|':_UIButtonBarButton:0x14c546b00 )>",
    "<NSLayoutConstraint:0x281556a80 'UIButtonBar.maximumAlignmentSize' _UIButtonBarButton:0x14c546b00.height == UILayoutGuide:0x280f41dc0'UIViewLayoutMarginsGuide'.height   (active)>",
    "<NSLayoutConstraint:0x281751a40 'UIView-bottomMargin-guide-constraint' V:[UILayoutGuide:0x280f41dc0'UIViewLayoutMarginsGuide']-(0)-|   (active, names: '|':_UIButtonBarStackView:0x1483bb0e0 )>",
    "<NSLayoutConstraint:0x28156b020 'UIView-bottomMargin-guide-constraint' V:[UILayoutGuide:0x280fc07e0'UIViewLayoutMarginsGuide']-(16)-|   (active, names: '|':_UIButtonBarButton:0x14c546b00 )>",
    "<NSLayoutConstraint:0x2817519a0 'UIView-topMargin-guide-constraint' V:|-(0)-[UILayoutGuide:0x280f41dc0'UIViewLayoutMarginsGuide']   (active, names: '|':_UIButtonBarStackView:0x1483bb0e0 )>"
)

• Multiple autolayout issues are reported in Annotation Popup:

(
    "<NSLayoutConstraint:0x2817f1900 UILabel:0x14c1ad730.centerY == Zotero.AnnotationViewHeader:0x14c15beb0.centerY   (active)>",
    "<NSLayoutConstraint:0x2817f1950 V:|-(9)-[UILabel:0x14c1ad730]   (active, names: '|':Zotero.AnnotationViewHeader:0x14c15beb0 )>",
    "<NSLayoutConstraint:0x2817f1c20 Zotero.AnnotationViewSeparator:0x14c141b20.height == 0.5   (active)>",
    "<NSLayoutConstraint:0x2817f2990 UIImageView:0x14c14ae00.height == 256   (active)>",
    "<NSLayoutConstraint:0x2817f2b20 V:|-(12.5)-[UIImageView:0x14c14ae00]   (active, names: '|':Zotero.AnnotationViewImageContent:0x14c14ac60 )>",
    "<NSLayoutConstraint:0x2817f29e0 V:[UIImageView:0x14c14ae00]-(12.5)-|   (active, names: '|':Zotero.AnnotationViewImageContent:0x14c14ac60 )>",
    "<NSLayoutConstraint:0x2817f2c60 V:|-(0)-[UIStackView:0x14c14b380]   (active, names: '|':Zotero.AnnotationView:0x14c110ff0 )>",
    "<NSLayoutConstraint:0x2817f2cb0 UIStackView:0x14c14b380.bottom == Zotero.AnnotationView:0x14c110ff0.bottom   (active)>",
    "<NSLayoutConstraint:0x2817f2f80 V:|-(3)-[Zotero.AnnotationView:0x14c110ff0]   (active, names: '|':UITableViewCellContentView:0x14c14b6a0 )>",
    "<NSLayoutConstraint:0x2817f2fd0 V:[Zotero.AnnotationView:0x14c110ff0]-(10)-|   (active, names: '|':UITableViewCellContentView:0x14c14b6a0 )>",
    "<NSLayoutConstraint:0x281007520 'UISV-canvas-connection' V:[Zotero.AnnotationViewImageContent:0x14c14ac60]-(0)-|   (active, names: '|':UIStackView:0x14c14b380 )>",
    "<NSLayoutConstraint:0x2817e9ae0 'UISV-canvas-connection' UIStackView:0x14c14b380.top == Zotero.AnnotationViewHeader:0x14c15beb0.top   (active)>",
    "<NSLayoutConstraint:0x281007660 'UISV-spacing' V:[Zotero.AnnotationViewSeparator:0x14c141b20]-(0)-[Zotero.AnnotationViewImageContent:0x14c14ac60]   (active)>",
    "<NSLayoutConstraint:0x2817d6940 'UISV-spacing' V:[Zotero.AnnotationViewHeader:0x14c15beb0]-(0)-[Zotero.AnnotationViewSeparator:0x14c141b20]   (active)>",
    "<NSLayoutConstraint:0x2817f47d0 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x14c14b6a0.height == 141.5   (active)>"
)