fix(weakRates): major progress in resolving bugs

bigs were introduced by the interface change from accepting raw molar abundance vectors to using the composition vector. This commit resolves many of these, including preformant ways to report that a species is not present in the composition and unified index lookups using composition object tooling.

BREAKING CHANGE:

src/include/gridfire/partition/composite/partition_composite.h

@@ -6,7 +6,6 @@
 #include "fourdst/logging/logging.h"
 
 #include <string>
-#include <unordered_map>
 #include <vector>
 
 #include <memory>
@@ -99,6 +98,6 @@ namespace gridfire::partition {
          * @return Unique pointer to a new PartitionFunction instance of the given type.
          * @throws std::runtime_error If the given type is not recognized.
 +         */
-         [[nodiscard]] std::unique_ptr<PartitionFunction> selectPartitionFunction(const BasePartitionType type) const;
+         [[nodiscard]] std::unique_ptr<PartitionFunction> selectPartitionFunction(BasePartitionType type) const;
      };
  }