alpkit: Add tests for generated JSON schemas #52

Job	Run time
Test on x86_64-alpine-linux-musl (dynamically linked)	58s
Run linters	43s
Test on x86_64-unknown-linux-musl with Rust stable	56s
Test on x86_64-unknown-linux-musl with Rust nightly	53s
Test on x86_64-unknown-linux-musl with Rust 1.64	1m 4s
Test on x86_64-unknown-linux-gnu with Rust stable	49s
Test on x86_64-apple-darwin with Rust stable	1m 1s
Test on aarch64-unknown-linux-musl with Rust stable	1m 4s
Test on aarch64-unknown-linux-gnu with Rust stable	1m 3s
Test on armv7-unknown-linux-musleabihf with Rust stable	1s
Test on powerpc64le-unknown-linux-gnu with Rust stable	1m 4s
Test on riscv64gc-unknown-linux-gnu with Rust stable	1m 5s
Test with --features shell-timeout	1s
Test with --features flate2-zlib --no-default-features	38s
Test with --features flate2-zlib-ng --no-default-features	55s
	12m 15s

Provide feedback