feat: introduce maximum parser recursion depth

Add a recursion depth limit to prevent stack overflow vulnerabilities
when parsing deeply nested Jsonnet expressions. This addresses potential
denial-of-service attacks where malicious inputs with excessive nesting
could crash the parser.

Key changes:
- Introduce MAX_PARSER_DEPTH constant (1000) to limit parser recursion
- Add depth parameter to all parsing functions
- Check depth limit before parsing recursively nested structures
- Throw clear error message when maximum depth is exceeded
- Improve documentation for parsing functions
- Add test case to verify limit enforcement

Signed-off-by: Ville Vesilehto <[email protected]>

Author: thevilledev