UID optimizations addressing BIT-1016.

Max UID bit-length is now 128, but can be increased w/ trivial source
code change of BRO_UID_LEN.
Add bits_per_uid unit test, addressing BIT0-1016.
Merge remote-tracking branch 'origin/topic/jsiwek/uid'

Thanks!

* origin/topic/jsiwek/uid:
  Add bits_per_uid unit test, addressing BIT0-1016.
  UID optimizations addressing BIT-1016.

BIT-1016 #merged
Updating submodule(s).

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