This change Ports R to make use of QProcess. Highlights of the changes are:
- Disable R server
- Make all the communication using QProcess (R's command line interface)
- Plotting is supported by but plots are not integrated in the worksheet
- Tab completion used to make use of RServer and hence it has been disabled for now
Differential Revision: https://phabricator.kde.org/D7565
Close T6116
BUG: 351871