Function parseConfigFromJson

Recursively parses and resolves a configuration object. Handles "globalConfig" merging, nested URLs, arrays, and indirect references.

For every key-value pair:

• If the value is an array, all entries are resolved and flattened.
• If the value is an object with "url" and "resolve" keys, it is replaced via that URL.
• If the value is a string ending in ".json" (excluding "tileset.json"), loads and resolves its content.
• If the value is a string ending in ".txt", reads comma-separated references and resolves each.
• Otherwise, leaves the value as is. If "globalConfig" exists as a key, its content is deeply merged with the resolved config using full replacement.