[ApolloPagination] Rename classes, make `GraphQLQueryPager` a publisher #825

Job	Run time
Cocoapods Integration Tests - macOS	20s
changes	6s
Run swift build for SPM packages (apollo-ios)	49s
Codegen Test Configurations - macOS	7m 38s
Run swift build for SPM packages (apollo-ios-codegen)	1m 8s
Run swift build for SPM packages (apollo-ios-pagination)	1m 38s
Run Tuist Generation	1m 11s
Verify Frontend Bundle Latest - macOS	0s
Apollo Integration Tests - macOS	0s
Apollo Unit Tests - macOS	11s
Codegen CLI Unit Tests - macOS	14s
Codegen Lib Unit Tests - macOS	45s
ApolloPagination Unit Tests - macOS	2m 50s
	16m 50s

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