Release candidate v2.16.0-rc.1

Noteworthy changes since the previous release:

• project renamed to TuneD to emphasize correct pronunciation
• fixed multiple inheritance problem where parents include a common ancestor (rhbz#182588)
• bootloader: added support for the rpm-ostree (rhbz#1950164)
• abstracted sched_* and numa_* tunings for kernel 5.13 and newer
• dropped python-schedutils and python-decorator dependencies
• realtime: changed the default to "isolcpus=domain,managed_irq,X-Y" (rhbz#1820626)
• net: fixed various tracebacks (rhbz#1943291, rhbz#1944686)
• realtime: improved profile verification (rhbz#1947858)
• updated TuneD profiles