feat(575): adding support for inline certificates/keys as base64 encoded

[gabrik]

Adds new fields in the TLS configuration, allowing users to inline certificates and keys as encoded base64 strings.

Added fields:

• root_ca_certificate_base64
• server_private_key_base64
• server_certificate_base64
• client_private_key_base64
• client_private_key_base64

Priority order when building the locator is:

• Inlined to the locator
• base64 certificate
• file certificate

If both the path and the base64 are present the TlsConfigurator returns an error.

Solves #575

[gabrik]

Just tested with a configuration like:

{
  "connect": {
    "endpoints": [
      "tls/REDACTED.routers.REDACTED.paas.zettascale.cloud:7447"
    ]
  },
  "id": "78b432a9634041acaf7c47665a40f4c5",
  "listen": {
    "endpoints": [
      "tls/0.0.0.0:7447"
    ]
  },
  "metadata": {
    "REDACTED"
  },
  "mode": "router",
  "transport": {
    "link": {
      "tls": {
        "client_auth": true,
        "client_certificate_base64": "LS0tLS1CRUdJTi...REDACTED",
        "client_private_key_base64": "LS0tLS1CRUdJTi...REDACTED",
        "server_certificate_base64": "LS0tLS1CRUdJTi...REDACTED",
        "server_private_key_base64": "LS0tLS1CRUdJTi...REDACTED",
        "root_ca_certificate_base64": "LS0tLS1CRUdJTi...REDACTED",
      }
    }
  }
}

[gabrik]

Given some security concerns, the fields should be wrapped in something like: secrecy.Secret to not expose them into logs/admin space.

[gabrik]

@milyin please check if this has an impact of your current work on the config

[milyin]

@gabrik Thank you for notification. Update looks good for me, my changes not affected