Adds a new setting, `bellStyle`, to be able to disable the audible bell
added in #7679. Currently, this setting accepts two values:
* `audible`: play a noise on a bell
* `none`: Don't play a noise.
In the future, we can add a `"bellStyle": "visible"` for flashing the
Terminal instead of making a noise on bell.
## Validation Steps Performed
Pressing <kbd>Ctrl+G</kbd> in cmd, and hitting enter is an easy way of
triggering a bell. I set the setting to `none`, and presto, the bell
stopped.
Closes#2360
98806e27b1