[dsl] Use constrainted constructors for PathVar as per code review #4

Job	Run time
Submit Dependencies (ubuntu-latest, temurin@8)	4m 51s
Generate coverage report (ubuntu-latest, 2.13.12, temurin@8)	4m 51s
Generate Site (ubuntu-latest, temurin@8)	4m 26s
Build and Test (ubuntu-latest, 3, temurin@8, rootJS)	4m 52s
Build and Test (ubuntu-latest, 3, temurin@8, rootJVM)	4m 52s
Validate Steward Config (ubuntu-latest, temurin@11)	17s
Build and Test (ubuntu-latest, 3, temurin@8, rootNative)	4m 50s
Build and Test (ubuntu-latest, 2.12, temurin@8, rootJS)	4m 52s
Build and Test (ubuntu-latest, 2.12, temurin@8, rootJVM)	4m 52s
Build and Test (ubuntu-latest, 2.12, temurin@8, rootNative)	4m 51s
Build and Test (ubuntu-latest, 2.13, temurin@8, rootJS)	4m 50s
Build and Test (ubuntu-latest, 2.13, temurin@8, rootJVM)	4m 52s
Build and Test (ubuntu-latest, 2.13, temurin@8, rootNative)	4m 54s
Build and Test (ubuntu-latest, 2.13, temurin@11, rootJVM)	4m 46s
Build and Test (ubuntu-latest, 2.13, temurin@17, rootJVM)	4m 53s
Publish Artifacts	1s
	1h 7m 50s

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