Improve Clojure callee coverage

[hahwul]

Summary

• add top-level Clojure defn callee indexing, including metadata-decorated handlers
• attach Reitit and Pedestal handler callees from symbols, quoted vars, syntax quotes, and inline fns
• add focused callee fixtures/specs for Reitit and Pedestal

Tests

• crystal spec spec/unit_test/miniparser/clojure_callee_extractor_spec.cr spec/functional_test/testers/clojure/reitit_callees_spec.cr spec/functional_test/testers/clojure/pedestal_callees_spec.cr --error-trace
• just test
• just build