Switch auto-generated IDs to Flake IDs from random UUIDs - #7531

…hout an incoming id.

Wire up the timestampUUID generator to indexing.

See elastic#5941

Incorporate some of the changes from @kimchy and @s1monw.
Move the UUID generators into their own classes and provide a common
interface as a first step to moving them under a singleton. Use a better
method of getting the mac address and fall back to a secure random address
if it fails. Add tests to test conccurency and shared prefix integrity of
UUIDs. Use PaddedAtomicLongs to hold the sequence number and lasttime.
Check to see if a time slip has occured as described by @s1monw in a CAS loop.
Next step is to move the impls under a singleton.

See elastic#5941

Reduce number of time bytes to 6 reducing total number of bytes to 20.
Validate that we have a mac address that contains data to avoid getting
addresses that are just 00:00:00:00:00:00 which can happen on virtualized
machines. Remove use of ByteBuffer on puts to reduce overhead. Add code to
attempt to prevent time slips.

See elastic#5941

Simplify mac address validation routing and remove unneed variable.