chore(scripts): add OCPI 2.2.1 registration walker

[MostafaMoradii]

Summary

• Add scripts/ocpi-register.sh — walks the OCPI 2.2.1 credentials handshake (GET /versions → GET /versions/{v} → POST /credentials) against a hub.
• Base64-encodes the Authorization: Token value (OCPI 2.2+ requirement), prints each request/response with status + headers + JSON-pretty body, and stops on the first 4xx/5xx so failures are obvious.
• Inputs come from env vars (HUB_BASE, TOKEN_A, MY_VERSIONS_URL, MY_TOKEN_B, COUNTRY_CODE, PARTY_ID); body shape is 2.2/2.2.1 (the script header notes how to adjust for 2.1.1).

Used today to diagnose a 401 Unauthorized on testapiv2.ortaksarjplatformu.com/ocpi/versions (token had been consumed; awaiting a fresh TOKEN_A).

Test plan

• bash -n scripts/ocpi-register.sh (syntax)
• Run with valid inputs against the test hub once a fresh TOKEN_A arrives; expect the three steps to print and POST /credentials to return our TOKEN_C
• Run with a bad TOKEN_A and confirm the script stops at step 1 with status 401