fix: fix parsing nested arrays

[andydunstall]

Fixes a bug parsing nested arrays in client mode.

When parse_stack_.emplace_back(len, cached_expr_) is called before creating the new array, the root array would be added to parse_stack_ twice and the leaf array would never be added. That means when a stack was popped, cached_expr_ would end up pointing to the wrong array.

Such as the array [[['foo'],['bar']],['car']] ("*2\r\n*2\r\n*1\r\n$3\r\nfoo\r\n*1\r\n$3\r\nbar\r\n*1\r\n$3\r\ncar\r\n") would have been parsed as [[['foo']],['bar'],['car']], since after foo was parsed such that the nested array was at capacity, popping the stack would end up pointing cached_expr_ to the root array instead of the first nested array.

[dranikpg]

Good catch 👍🏻