ILCompilerTargetsPath used in PublishAot is sometimes empty.

[LakshanF]

The comment, #30091 (comment), has context where the property, ILCompilerTargetsPath, can be empty. Investigate to assess if this scenario should be covered for NativeAot.

We should do a review of NativeAOT scenarios for SDK post-implicit package work, including the need for 2 packages. @ViktorHofer has some additional comments on ways to improve the experience.

cc @sbomer