Align CLI behavior with go-jsonnet

[He-Pin]

Motivation

sjsonnet CLI should be a go-jsonnet-compatible superset for applicable CLI behavior, while making remaining intentional differences explicit.

Modification

• Allow --help / --version without an input file and keep control flags inactive when they are option values or after --.
• Align -J priority with go-jsonnet right-most-wins behavior while keeping JSONNET_PATH lower priority.
• Align YAML stream, output-file newline, create-output-dirs, max-trace, and -- terminator behavior with go-jsonnet where applicable.
• Harden short-option normalization for attached values such as -Jdir and -n4.
• Keep sjsonnet's existing CLI tail-call optimization behavior and test it explicitly.

Result

Case	go-jsonnet v0.22.0	jrsonnet 0.5.0-pre99	sjsonnet before	sjsonnet after
--version without input	prints version	prints version	parser error	prints Sjsonnet 0.7.1-SNAPSHOT
--help without input	prints help	prints help	parser error	prints help without parser noise
-- --version with file named --version	evaluates file	evaluates file	parser error	evaluates file
-J a -J b duplicate import path	imports from b	imports from b	imports from a	imports from b
--yaml-stream -e '[{a:1},{b:2}]'	JSON document stream with ---	YAML document stream	old stream formatting	JSON document stream with ---
--max-stack 2 non-tail recursion	stack error	stack error	stack error	stack error
--max-stack 2 tail recursion	stack error	stack error	returns 0 via TCO	returns 0 via TCO
-Jdir / -n4 attached values	not supported for -Jdir	supported	broken short cluster parsing	supported as sjsonnet robustness

References

• Local behavior checks against go-jsonnet v0.22.0 and jrsonnet 0.5.0-pre99.