Add iterator traits to emp::array iterator #1022

Job	Run time
Measure Test Coverage	1m 36s
Tests (clang++, test-native-regular)	26m 27s
Test Documentation Build	12s
Test Tidy Enforcement on macOS	4m 29s
Tests (clang++, test-native-fulldebug)	4m 27s
Tests (clang++, test-native-opt)	46m 24s
Tests (clang++, test-examples)	2m 2s
Tests (clang++, test-demos)	3m 7s
Web Tests	5m 51s
Enforce Tidyness	42s
Tests (g++, test-native-regular)	21m 39s
Tests (g++, test-native-fulldebug)	4m 53s
Tests (g++, test-native-opt)	49m 10s
Tests (g++, test-examples)	4m 6s
Tests (g++, test-demos)	3m 18s
Deploy to DockerHub	0s
	2h 58m 23s

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