Constants defined in C extensions might be attributed other the gems

Some constants like `ERB::Escape` that are defind in C extension
components of gems are currently failing the `defined_in_gem?` look up.

This happens for `ERB::Escape` because, instead of
`erb/lib/erb/utils.rb` loading the shared-object for `escape`, we have
`erubi` loading it. Thus, when we do the backtrace scan to find the file
that is loading the constant we attribute it to the `erubi` gem. This is
because there are no frames in the backtrace for the class definition
coming from a C extension, thus we miss the actual file that does the
`ERB::Escape` definition.

Since we can look up the source location of constants now, it makes more
sense to include that in the list of file candidate locations. Which
makes it resilient against these kinds of mistakes.

Author: paracycle

lib/tapioca/runtime/reflection.rb

@@ -213,9 +213,16 @@ def resolve_loc(locations)
 
       #: (T::Module[top] constant) -> Set[String]
       def file_candidates_for(constant)
-        relevant_methods_for(constant).filter_map do |method|
+        # Grab all source files for (relevant) methods defined on the constant
+        candidates = relevant_methods_for(constant).filter_map do |method|
           method.source_location&.first
         end.to_set
+
+        # Add the source file for the constant definition itself, if available.
+        source_location_candidate = const_source_location(name_of(constant).to_s)&.file
+        candidates.add(source_location_candidate) if source_location_candidate
+
+        candidates
       end
 
       #: (T::Module[top] constant) -> untyped