Add IsFirst/IsLast methods to match SS5 conventions (closes #1274) #1142

Job	Run time
CI / Generate matrix	16s
CI / Context	1s
CI / Check governance	0s
CI / 8.1 prf-low mysql57 phpunit all	3m 30s
CI / 8.2 mariadb phpunit all	2m 57s
CI / 8.3 mysql80 phpunit all	3m 1s
CI / 8.1 mysql57 phplinting	1m 44s
CI / 8.1 mysql57 endtoend root job1	8m 46s
CI / 8.3 mysql80 endtoend root job1	8m 27s
CI / 8.1 mysql57 endtoend root job2	7m 48s
CI / 8.3 mysql80 endtoend root job2	8m 20s
CI / 8.1 mysql57 endtoend root job3	9m 15s
CI / 8.3 mysql80 endtoend root job3	9m 26s
CI / 8.1 mysql57 endtoend root job4	9m 5s
CI / 8.3 mysql80 endtoend root job4	9m 13s
CI / 8.1 mysql57 endtoend root job5	7m 0s
CI / 8.3 mysql80 endtoend root job5	6m 1s
CI / 8.1 mysql57 endtoend root job6	8m 22s
CI / 8.3 mysql80 endtoend root job6	8m 35s
CI / 8.1 mysql57 endtoend root job7	11m 12s
CI / 8.3 mysql80 endtoend root job7	11m 40s
CI / 8.1 mysql57 js	5m 8s
CI / 8.1 mysql57 doclinting	2m 53s
CI / Dispatch tag patch release	0s
	2h 22m 40s

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