Count empty containers toward parser nesting limits

[ydah]

The parser skips the nesting check for empty arrays and objects, accepting structures that the generator rejects with the same max_nesting setting.

require "json"

JSON.parse("[[]]", max_nesting: 1)
# Before: [[]]
# After: raises JSON::NestingError, matching JSON.generate([[]], max_nesting: 1).

Check the nesting limit before handling empty containers in both the C and Java parsers. Add regression tests for empty arrays and objects, including ResumableParser with split input.

[byroot]

Thanks but this was deliberate. The goal of max_nesting isn't to be particularly precise, but to protect against DOS style of attacks. I chose to skip the depth increment/decrement for empty containers for performance reasons.