chore: merge source_{reader,acker} impl into one (#2102) #1146

Job	Run time
build-rust-arm64	4m 32s
build-rust-amd64	4m 24s
Build binaries	2m 16s
Build & push linux/amd64 and linux/arm64 (numaflow)	2m 5s
Bom	1m 9s
Release	28s
	14m 54s

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