[chore] [pkg/ottl] Introduce `ctxutil.GetMap()` and `ctxutil.GetMapKeyName()` internal functions #33689

Job	Run time
arm-unittest-matrix (receiver-1)	8m 7s
arm-unittest-matrix (processor-1)	5m 1s
arm-unittest-matrix (receiver-3)	5m 56s
arm-unittest-matrix (processor-0)	4m 23s
arm-unittest-matrix (exporter-1)	9m 13s
arm-unittest-matrix (receiver-0)	5m 48s
arm-unittest-matrix (exporter-0)	4m 6s
arm-unittest-matrix (pkg)	5m 39s
arm-unittest-matrix (exporter-3)	5m 26s
arm-unittest-matrix (cmd-0)	3m 9s
arm-unittest-matrix (extension)	6m 15s
arm-unittest-matrix (receiver-2)	9m 45s
arm-unittest-matrix (other)	4m 36s
arm-unittest-matrix (exporter-2)	4m 49s
arm-unittest-matrix (internal)	6m 50s
arm-unittest-matrix (connector)	4m 59s
arm-unittest	4s
flakytests-generate-issues	0s
	1h 34m 6s

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