Change order of equality check to favor cheaper checks first
Change order of equality check to favor cheaper checks first

Comparing two strings is much cheaper than isinstance, so we should try
those first

A performance test was run on a network with 170 devices running Zeroconf.
There was a ServiceBrowser running on a separate thread while a timer ran
on the main thread that forced a thread switch every 2 seconds (to include
the effect of thread switching in the measurements). Every minute,
a Zeroconf broadcast was made on the network.

This was ran this for an hour on a Macbook Air from 2015 (Intel Core
i7-5650U) using Ubuntu 19.10 and Python 3.7, both before this commit and
after.

These are the results of the performance tests:
Function		Before count		Before time	Before time per count	After count		After time		After time per count	Time reduction
DNSEntry.__eq__		528			0.001s		1.9μs			538			0.001s			1.9μs			1.9%
DNSPointer.__eq__	24369256 (24.3M)	134.641s	5.5μs			25989573 (26.0M)	86.405s			3.3μs			39.8%
DNSText.__eq__		52966716 (53.0M)	190.640s	3.6μs			53604915 (53.6M)	169.104s		3.2μs			12.4%
DNSService.__eq__	52620538 (52.6M)	171.660s	3.3μs			56557448 (56.6M)	170.222s		3.0μs			7.8%

jstasiak/python-zeroconf