Refactor freqman_db parsing (#1244)

* WIP freqman changes/memory perf/stash
* Split ui tone_key function out for testing.
* Add more tests and fix bugs.
* Use default max_entries in recond
* Set limit back to 90 for now

firmware/application/apps/ui_recon.hpp

@@ -67,6 +67,7 @@ class ReconView : public View {
     void set_loop_config(bool v);
     void clear_freqlist_for_ui_action();
     void reset_indexes();
+    void update_description();
     void audio_output_start();
     bool check_sd_card();
     size_t change_mode(freqman_index_t mod_type);
@@ -87,6 +88,10 @@ class ReconView : public View {
     // placeholder for possible void recon_start_recording();
     void recon_stop_recording();
 
+    // Returns true if 'current_index' is in bounds of frequency_list.
+    bool current_is_valid();
+    freqman_entry& current_entry();
+
     jammer::jammer_range_t frequency_range{false, 0, MAX_UFREQ};  // perfect for manual recon task too...
     int32_t squelch{0};
     int32_t db{0};