#[pdf_file_test_cases]Expand description
Glob *.pdf, *.pdf.link files in sample_files, ../pdf/, pdf.js/test/pdfs directories,
relative to crate directory.
for each file generate a test, using #[test-case] attribute.
For example: #[test_case("sample_files/normal/foo.pdf")]
To save compile time, file list cached in ${workspace}/target/render-test.list file, if file
not exist, it will re-generated by directories. Each line in cache file is a file path.
Using proc-macro2, syn, quote crates to help for parsing and generating code.