runners/sessions: improve conditions for match adding
- Use the appropriate
SessionManager::canXYZ()
checks for each of the commands to add matches and syntaxes for. - Handle the trigger keywords such that there are no duplicates in the translated strings
- Add additional keywords to trigger listing all sessions.
- Change texts and add subtexts to make it consistent with how the entries are displayed in the application launcher and the powerdevil runner.
- Some code cleanup.
Edited by Natalie Clarius