Initial Release of glsl-preprocessor with GLSL Passthrough Features

This is the initial functioning release of glsl-preprocessor based on JCPP. The following are changes made compared to the upstream version of JCPP.

• Removed checked exceptions
• Moved file system-related things into the fs package
• Added virtual file system functionality and improved string-handling aspects in Preprocessor
• Removed file system reading classes. The only file system reading functionality is now ResourceFileSystem that is used for testing
• Added virtual and in-memory file system classes and functionality
• Added support for GLSL-specific directives like #extension, #version, #custom, and a different type of #line that only uses numbers
• Added snapshot and error tests for GLSL-specific situations and functionality
• Removed guava and replaced it with builtin methods from the standard library
• Removed dead code and cleaned up some things

Meta:

• Reformatted much of the code
• Upgraded the source compatibility to Java 17 (LTS)
• Added jacoco coverage testing

This library isn't directly connected to glsl-transformer but it is useful as a preprocessing step as glsl-transformer expects already preprocessed code. Furthermore it shares some of the testing code and build configuration.

Initial release for testing purposes

This release was mostly cleanup and was published only to test that the publication works with this setup. Release notes for this and the following release can be found in the following release.