scxtop: Implement searchable events

[hodgesds]

Once #1220 is merged a search function should be implemented for perf events. Pressing the e key renders the event selection interface. This will be a tricky feature to implement due to the fact that keybindings will need to be aware of the AppState. In order to make this work it might require a new AppState, something like TextInput. When events are handled they are handled based on the key map. However, this should be made aware of the AppState so that in the TextInput state any keys are passed directly to handle_action function. From there it will need to keep a buffer of the input on the App struct and use that buffer for filtering events in render_event_list. Ideally fuzzy matching would be supported similar to skim but a substring match is fine for a first implementation.