chore: Plumb context.Context throughout polling datasourcev2 (#234) #412

Job	Run time
go-versions / go-versions	5s
Windows, Go 1.23	1m 37s
Windows, Go 1.22	1m 46s
Windows, Go 1.18	1m 3s
Linux, Go 1.18 / Contract Tests	1m 24s
Linux, Go 1.18 / Benchmarks	4m 41s
Linux, Go 1.22 / Benchmarks	4m 30s
Linux, Go 1.18 / Unit Tests and Coverage	1m 0s
Linux, Go 1.22 / Contract Tests	1m 28s
Linux, Go 1.22 / Unit Tests and Coverage	48s
Linux, Go 1.23 / Benchmarks	4m 27s
Linux, Go 1.23 / Contract Tests	1m 24s
Linux, Go 1.23 / Unit Tests and Coverage	51s
	25m 4s

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