Support multiline directives in connection file parser

[gnzjgo]

Problem

The connection file parser does not support multiline directives using the > block syntax. This is needed for KAFKA_SSL_CA_PEM when providing SSL/TLS certificates in PEM format (e.g. for Aiven Kafka or self-signed certs).

A connection file like this fails to parse:

TYPE kafka
KAFKA_BOOTSTRAP_SERVERS localhost:9092
KAFKA_SSL_CA_PEM >
    -----BEGIN CERTIFICATE-----
    MIIDXTCCAkWgAwIBAgIJAM...
    -----END CERTIFICATE-----

The parser iterates line-by-line and treats the indented certificate lines as unknown directives, raising MigrationParseError.

Solution

• Update the connection parser to use an index-based loop and read_directive_block() (already used by datasource/pipe parsers) to handle KAFKA_SSL_CA_PEM > multiline blocks.
• Update the connection generator to emit the > block syntax when ssl_ca_pem contains newlines.
• Single-line KAFKA_SSL_CA_PEM values (e.g. {{ tb_secret(...) }}) continue to work as before.

Ref: tinybirdco/tinybird-sdk-typescript#129