Replace font loading with general-purpose ResourceWalker

[ghost]

https://github.com/asciidocfx/AsciidocFX/blob/91679fe90bd2debe238ed1e0721e0e2aaf36fe72/src/main/java/com/kodedu/boot/AppStarter.java#L105

Consider using a walking the resources instead of hard-coding font names within the source code:

• https://github.com/DaveJarvis/keenwrite/blob/master/src/main/java/com/keenwrite/util/ResourceWalker.java
• https://github.com/DaveJarvis/keenwrite/blob/6cf6c79989cf8923b36c4ca35c9593e6d8b34f40/src/main/java/com/keenwrite/Main.java#L113

This also avoids a little repetition in the code. Note that the resource stream in AsciidocFX is not closed, which could be considered a bug (times seven because of the code duplication).

[rahmanusta]

Hi, thank you, this is true that we have to close the open stream here. Any pull requests are welcome. ResourceWalker is nice, and I like it.