Support participant onboarding

[mikeus9908]

Add an API endpoint that generates a new identity in Sedimark.
The caller must provide:

• Service endpoint(s)
• Subject claims (TBD)

The booth should complete the onboarding operations:

• Create identity and evm keypairs
• Create new DID Document and upload on the DLT
• Communicate with the issuer for obtaining a valid Verifiable Credential

[psotres]

Example of SEDIMARK preliminary VC:

------------------------ JWT header -----------------------
{
  "kid": "did:iota:rms:0x2b7ac707e71eda93135e1a457718f2d87f387ff66d62c8084ef06301110086ef#W1lJ9vr23XhK8kV8YTu27njdBBwjtHG0AWoNveHGD18",
  "typ": "JWT",
  "alg": "EdDSA"
}
------------------------ JWT Payload ----------------------
{
  "exp": 1762939547,
  "iss": "did:iota:rms:0x2b7ac707e71eda93135e1a457718f2d87f387ff66d62c8084ef06301110086ef",
  "nbf": 1731317147,
  "jti": "[https://example.market/credentials/22"](https://example.market/credentials/22%22),
  "sub": "did:iota:rms:0x3f6d68268dfbe4773065d46b04aec98d35d3bfcca4282649ed256b97d1834a38",
  "vc": {
    "@context": "[https://www.w3.org/2018/credentials/v1"](https://www.w3.org/2018/credentials/v1%22),
    "type": [
      "VerifiableCredential",
      "MarketplaceCredential"
    ],
    "credentialSubject": {
      "name": "Michele",
      "surname": "Festa",
      "userOf": "SEDIMARK marketplace"
    }
  }
}
------------------------ signature ------------------------
qE5IUBstqp5umFtcYXuNZx9QintXLuz5vSWh46CQKmRv9PW3m5QvZy0uW_xaH_rBP9TI5wddAUF8pEoKKkW1CA