Add RFC 6570 query parameter support to resource templates

[jlowin]

FastMCP already supported RFC 6570 simple expansion ({var}) and wildcard parameters ({var*}). This adds form-style query parameters ({?param1,param2}) to complete our RFC 6570 implementation.

Query parameters provide a clean way to pass optional configuration to resources. Parameters declared with {?...} syntax can be overridden via query string, while optional parameters omitted from the template always use their defaults.

@mcp.resource("data://{id}{?format,limit}")
def get_data(id: str, format: str = "json", limit: int = 10) -> str:
    return f"id={id}, format={format}, limit={limit}"

# Client calls:
# data://123 → uses defaults
# data://123?format=xml → overrides format
# data://123?format=csv&limit=50 → overrides both

Type coercion happens automatically based on function type hints (int, float, bool, str).