Review user interaction in session management

Summary:

• SessionManageDialog
  • Build user interface by ui file
  • Avoid obsolete Qt members
  • Choose more meaningful member names
  • Add filter field and sort button
  • Open session by double click
  • Add buttons for "Copy" and "Open as Template"
  • Reorder a couple of code to be a little bit more logic ordered
  • Delete a session with delay which offer a restore and avoid annoying confirmation dialog
  • Rename a session inside of the list view to avoid extra popup window to enter the new name.

• Remove SessionOpenDialog, use SessionManageDialog instead
• Remove SessionChooser, use SessionManageDialog instead

• SessionManager
  • Add signal sessionListChanged() To avoid unneded signals is updateSessionList() slightly modified with a clearer look and an added check for changes in an easy way.
  • Add copySession()
  • Let rename/copySession() ask for a new name when needed
  • Move session creation parts from newSessionName() to sessionSaveAs()
  • Rename newSessionName() to askForNewSessionName()
  • Add suggestNewSessionName()
  • Don't create anonymous session in ctor
  • Don't save anonymous session as last session

• MainWindow
  • Remove from sessions menu "Open Session" because it's now the same as "Manage Sessions"

Test Plan:

Reviewers: Kate, dhaumann, ngraham, VDG, cullmann

Reviewed By: Kate, dhaumann, cullmann

Subscribers: fabianr, anthonyfieroni, cullmann, kwrite-devel, Kate

Tags: Kate

Differential Revision: https://phabricator.kde.org/D16926