fix: do not declare _typecheck[_test] target when using tsc as transpiler

[jbedard]

Declaring the _typecheck[_test] targets is only required when tsc is not doing the typechecking while transpiling something.

We did add the _types target 100% of the time, transpiler(s) or not, which I think we should still keep. But when should the _typecheck[_test] targets be added? This reverts back to be more like before #705.

Fix #719

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Changes are visible to end-users: no

Test plan

• Covered by existing test cases
• New test cases added

[aspect-workflows]

Test

3 test targets passed

Targets

//examples/transpiler:custom_dts_transpiler-no_declarations-test [k8-fastbuild] 21ms
//examples/transpiler:custom_dts_transpiler-test [k8-fastbuild]                 26ms
//examples/transpiler:typecheck_fail-custom_transpilers_test [k8-fastbuild]     26ms

Total test execution time was 73ms. 97 tests (97.0%) were fully cached saving 8s.

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