Fastly Compute module 1.4.0

Add Model Context Protocol (MCP) support
Introduce datadome_mcp_endpoint configuration parameter to specify the MCP Endpoint (defaults to /mcp)
Collect Signature, Signature-Agent, and Signature-Input headers from requests to support HTTP message signatures as defined by RFC 9421
Collect Skyfire-Pay-ID header for AI bot monetization
Increase length limit from 128 to 512 characters for DataDome cookie to support future capabilities
Introduce datadome_graphql_endpoint configuration parameter to specify the GraphQL Endpoint (default to /graphql)
Improve core logic of our DataDome integration to support future capabilities