Remove `node-fetch` dependency from SDK, introduce `@realm/fetch` and allow passing `fetch` through `AppConfiguration` #3863

Job	Run time
Build for linux x64	2m 48s
Build for linux arm	5m 52s
Build for linux arm64	2m 13s
Build for windows x64	4m 46s
Build for windows ia32	5m 34s
Build for android x86_64	1m 46s
Build for android armeabi-v7a	1m 46s
Build for android arm64-v8a	2m 9s
Build for android x86	1m 46s
Build for darwin x64	2m 53s
Bundle TypeScript	1m 9s
Build for darwin arm64	2m 56s
Build for ios simulator	2m 9s
Build for ios catalyst	2m 25s
Build for ios ios	2m 14s
Generate Info.plist with all frameworks in place	29s
Test node on linux (test:ci)	8m 53s
Test electron on linux (test:ci:main)	6m 24s
Test electron on linux (test:ci:renderer)	6m 41s
Test electron on darwin (test:ci:main)	12m 16s
Test electron on darwin (test:ci:renderer)	9m 37s
Test node on darwin (test:ci)	13m 18s
Test react-native on android (test:ci:android)	24m 40s
Test react-native on ios (test:ci:ios)	22m 19s
	2h 27m 3s

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