Configure Konsole dialog GUI redesign

Summary:
* Use custom dialog and configuraton classes, as counterparts from KF5
  are bugged. The KF5 versions should be fixed and used here.
  * Create new KConfigDialog-like class and use it to show existing
    configuration pages.
  * Create KConfigDialogManager-like class for managing QButtonGroups.

* Remove help button from configuration dialog. There is nothing about
  configuration dialog options in the help.

* Profile Settings:
  * Use QTreeView instead of QTableView - it highlights whole lines,
    aligns header names to the left, etc. Basically it looks like lists
    in file manager or e.g. plugin list in Kate.
  * Use (default) QStyledItemDelegate with checkbox instead of custom
    delegate (tick mark) in favorite/show column.
  * Change default profile item style - it now has italics font and
    "(default)" suffix.
  * Disable "Delete" button when default profile is selected
  * Use slightly extended QKeySequenceEditor. KKeySequenceWidget looks
    heavily out of place in a tree view. New editor supports some
    control keys:
    * Esc key cancels key capture.
    * Del/backspace removes shortcut.
    * Enter confirms shortcut immediately.
    * Tab/backtab commits currently edited shorcut and moves to
      next/previous shortcut.
  * Shortcuts for non visible profiles use disabled text color.
  * Note about visibility and shortcuts

* Rename "File Location" to "Temporary Files"
  * Enable path selector only when "custom" is selected
  * Place paths directly in labels

* Disable all tabbar settings except visibility when visibility is set
  to "Never"

* Minor string changes.

**Screenshots**

{F6893460}
{F6893461}
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BUG: 404096
FIXED-IN: 19.08.0

Reviewers: #konsole, #vdg, ngraham

Reviewed By: #vdg, ngraham

Subscribers: ngraham, hindenburg, #vdg, konsole-devel, #konsole

Tags: #konsole, #vdg

Differential Revision: https://phabricator.kde.org/D20816