Add `mapOrKeepIn` / `flatMapOrKeepIn` to `F[Option[A]]` and `F[Either[A,B]]` syntaxes #828

Job	Run time
Generate Site (ubuntu-latest, temurin@17)	1m 11s
Submit Dependencies	0s
Build and Test (ubuntu-22.04, 2.12, temurin@8, rootJS)	2m 45s
Build and Test (ubuntu-22.04, 2.12, temurin@8, rootJVM)	2m 10s
Build and Test (ubuntu-22.04, 2.12, temurin@8, rootNative)	3m 8s
Build and Test (ubuntu-22.04, 3, temurin@8, rootJS)	2m 46s
Build and Test (ubuntu-22.04, 3, temurin@8, rootJVM)	2m 20s
Build and Test (ubuntu-22.04, 3, temurin@8, rootNative)	3m 14s
Build and Test (ubuntu-22.04, 2.13, temurin@8, rootJS)	2m 35s
Build and Test (ubuntu-22.04, 2.13, temurin@8, rootJVM)	2m 6s
Build and Test (ubuntu-22.04, 2.13, temurin@8, rootNative)	3m 6s
Build and Test (ubuntu-22.04, 2.13, temurin@17, rootJVM)	1m 30s
Publish Artifacts	0s
	26m 51s

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