Support large routing requests via POST and PUT

[pcace]

Summary

This change adds request-body support for standalone /brouter routing requests so large nogos, polylines, and polygons no longer have to fit into the URL.

This PR is based on a clean branch from upstream/master and contains only the standalone request-body support change.

What changed

• accept routing parameters via POST and PUT request bodies for /brouter
• keep existing GET query parameter support unchanged
• add request-body parsing safeguards based on Content-Type and Content-Length
• add a configurable maxRequestLength server property
• raise the standalone startup script defaults to support bodies slightly above 5 MiB
• document the request-body workflow and file-based PUT uploads
• add tests for POST body routing and large polygon PUT requests

Notes

• supported routing body content types are application/x-www-form-urlencoded and text/plain
• the standalone script now exposes the relevant JVM and request-size settings through environment variables

Validation

• built successfully in the project Docker build
• verified routing with GET and PUT locally
• verified a real PUT request with a body slightly above 5 MiB against a deployed server

[EssBee59]

==> no longer have to fit into the URL

Hello pcace!

Could you please first explain the need for implementing POST requests?
(I am missing defects about that)
The URL max size has been extended again and again in the last years, so that I thought, the GET requests support any real routing request currently?