Explicitly only use `FoundationEssentials` where possible #354

Job	Run time
Semantic Version label check	6s
musl	1m 28s
Unit tests / Construct unit test matrix	3s
Integration Tests / Test archive plugin	2m 19s
Integration Tests / Test Examples/APIGateway on 6.0.1-amazonlinux2	1m 18s
Integration Tests / Test Examples/BackgroundTasks on 6.0.1-amazonlinux2	1m 14s
Soundness / API breakage check	1m 48s
Integration Tests / Test Examples/HelloJSON on 6.0.1-amazonlinux2	1m 12s
Soundness / Broken symlinks check	2s
Integration Tests / Test Examples/HelloWorld on 6.0.1-amazonlinux2	1m 18s
Integration Tests / Test Examples/S3_AWSSDK on 6.0.1-amazonlinux2	4m 18s
Soundness / Documentation check	1m 31s
Soundness / License headers check	4s
Integration Tests / Test Examples/S3_Soto on 6.0.1-amazonlinux2	4m 42s
Integration Tests / Test Examples/Streaming on 6.0.1-amazonlinux2	1m 13s
Soundness / Unacceptable language check	5s
Soundness / Format check	34s
Soundness / Python lint check	6s
Soundness / Shell check	36s
Soundness / YAML lint check	3s
Swift 6 Language Mode / Swift 6 language mode	1m 14s
Unit tests / Unit tests / Linux (6.0)	1m 15s
Unit tests / Unit tests / Linux (nightly-6.0)	1m 32s
Unit tests / Unit tests / Linux (nightly-main)	1m 30s
	29m 31s

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