Rename project

This MR has the minimal ground work to rename the project on the surface:

• All D-Bus services claim new names, in addition to the old ones:
  • org.freedesktop.LocalSearch3
  • org.freedesktop.LocalSearch3.Control
  • org.freedesktop.LocalSearch3.Writeback
• CLI has been separated into its own localsearch3 executable
• All service executables have been renamed
• Install locations in share/lib dirs have been changed
• Additional D-Bus service files are installed to keep everything D-Bus activatable through old/new names
• Manpages got renamed
• Docs now reference new DBus names, and the LocalSearch name.

Not changed:

• D-Bus paths/interfaces are still /org/freedesktop/Tracker3/... / org.freedesktop.Tracker3...
• GSettings schemas/paths are still org.freedesktop.Tracker3... / /org/freedesktop/tracker3/...

These changes allow backwards compatible interaction with all user facing interfaces (SPARQL endpoint, and control/writeback services) through the old D-Bus names.

#346