Genex: Optimize usage requirement TARGET_PROPERTY recursion

In large projects the generation process spends a lot of time evaluating
usage requirements through transitive interface properties on targets.
This can be seen in a contrived example with deep dependencies:

    set(prev "")
    foreach(i RANGE 1 500)
      add_library(a${i} a.c)
      target_compile_definitions(a${i} PUBLIC A${i})
      target_link_libraries(a${i} PUBLIC ${prev})
      set(prev a${i})
    endforeach()

For each usage requirement (such as `INTERFACE_COMPILE_DEFINITIONS` or
`INTERFACE_INCLUDE_DIRECTORIES`), the value of the generator expression
`$<TARGET_PROPERTY:target,prop>` includes the values of the same
property from the transitive closure of link libraries of the target.

Previously we computed this by constructing a generator expression
string like `$<TARGET_PROPERTY:lib,INTERFACE_COMPILE_DEFINITIONS>` and
recursively evaluating it with the generator expression engine.  Avoid
the string construction and parsing by creating and using a dedicated
evaluation method `cmGeneratorTarget::EvaluateInterfaceProperty` that
looks up the properties directly.

Issue: #18964, #18965

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