* reimplement custom audio loading for `toast` and `key_click` using `from_mp3`
* run cargo fmt
* `try_bytes_from_config`: output with `log::trace` when file cannot be opened
* rewrite `try_bytes_from_config`
* use file `read_to_end`, log categories
* edit `register_wgui_samples`
* rework audio functions for loading custom wgui sounds
oh hey, it works!
* clean up
* allow custom `startup` and `app_start` sounds
these sounds are loaded on-demand and never registered; this behaviour is unchanged
* edit `bytes_from_config` outputs
* use return value of `read_to_end` instead of `len()` for reported file size
* implement suggested changes
- remove now-unused `register_mp3_sample_from_assets` function
- replace implementation of `try_bytes_from_config`
- missing the `real_path` context
* swap out `context`s for `inspect_err`s with closures to output `real_path`
* clean up `audio.rs`
- remove unused import
- unify capitalisation + quotes in output messages.
