Using the characters ( and ) in the font name will generate an invalid CSS Example

[jakejackson1]

Description
If adding a new font via GPDFAPI::add_font() and it includes the character ( or ) the developer template sample will not display with the correct reference name.

Step To Reproduce
Steps to reproduce the behavior:

1. Add a font with GPDFAPI::add_font()
2. Open the Font Manager
3. Select one of the fonts
4. Open the developer code sample in the right pane

Expected behavior
The font family reference is correct

Screenshots

Additional context
It isn't possible to get into this state through the UI as we prevent non-alpha numeric characters in the font name. Let's allow this character in the font name but strip it when generating the font key.