This PR introduces basic Kafka API version negotiation in Sarama by
enabling the client to restrict the API version for each request based
on the version ranges advertised by brokers in the initial `ApiVersions`
request/response - which is now executed synchronously as part of the
broker connection process, rather than as a fire-and-forget deferred
goroutine, and before SASL authentication takes place (but after
SSL/TLS, as indicated by the [Kafka protocol
docs](https://kafka.apache.org/26/protocol.html#api_versions)).

The selected version is the highest supported by both the broker and the
user-defined `Config.Version` upper bound.

To support this dynamic selection, a new `setVersion(int16)` method has
been added to the `protocolBody` interface, exposing the
request/response structs' `Version` field to be set externally.

Also, it defines constants for message keys, and replaces some (read:
those I found) usages of numeric literals to use the constants instead.

I experimented with extracting more logic from `protocolBody`
implementations, too, such as centralizing `requiredVersion()`,
`isValidVersion()`, and the "max protocol version for Kafka version"
selection in most Request constructors [as suggested by @dnwe in my
previous
PR](#3170 (comment));
however, while they can certainly simplify the code, I found these were
significantly larger-scale changes (and kinda out of scope for the
purpose of this PR), and decided to leave them out to keep this PR short
and easy to review.

<details>
<summary>Motivation behind the change: Sarama incompatibility with
Redpanda</summary>

The latest `github.com/IBM/sarama` version fails to connect to Redpanda
brokers (latest version too):

- Redpanda rejects the request with `Unsupported version 10 for metadata
API`
- sarama fails with `kafka: client has run out of available brokers to
talk to: EOF`

<details>
<summary>Sarama logs</summary>
```
2025/05/13 18:26:29 Initializing new client
2025/05/13 18:26:29 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
2025/05/13 18:26:29 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
2025/05/13 18:26:29 client/metadata fetching metadata for all topics from broker localhost:9092
2025/05/13 18:26:29 Connected to broker at localhost:9092 (unregistered)
2025/05/13 18:26:29 client/metadata got error from broker -1 while fetching metadata: EOF
2025/05/13 18:26:29 Closed connection to broker localhost:9092
2025/05/13 18:26:29 client/metadata no available broker to send metadata request to
2025/05/13 18:26:29 client/brokers resurrecting 1 dead seed brokers
2025/05/13 18:26:29 Error while sending ApiVersionsRequest to broker localhost:9092: kafka: broker not connected
2025/05/13 18:26:30 client/metadata retrying after 250ms... (2 attempts remaining)
2025/05/13 18:26:30 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
2025/05/13 18:26:30 client/metadata fetching metadata for all topics from broker localhost:9092
2025/05/13 18:26:30 Connected to broker at localhost:9092 (unregistered)
2025/05/13 18:26:30 client/metadata got error from broker -1 while fetching metadata: EOF
2025/05/13 18:26:30 Closed connection to broker localhost:9092
2025/05/13 18:26:30 client/metadata no available broker to send metadata request to
2025/05/13 18:26:30 client/brokers resurrecting 1 dead seed brokers
2025/05/13 18:26:30 client/metadata retrying after 250ms... (1 attempts remaining)
2025/05/13 18:26:30 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
2025/05/13 18:26:30 client/metadata fetching metadata for all topics from broker localhost:9092
2025/05/13 18:26:30 Connected to broker at localhost:9092 (unregistered)
2025/05/13 18:26:30 client/metadata got error from broker -1 while fetching metadata: EOF
2025/05/13 18:26:30 Closed connection to broker localhost:9092
2025/05/13 18:26:30 client/metadata no available broker to send metadata request to
2025/05/13 18:26:30 client/brokers resurrecting 1 dead seed brokers
2025/05/13 18:26:30 client/metadata retrying after 250ms... (0 attempts remaining)
2025/05/13 18:26:30 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
2025/05/13 18:26:30 client/metadata fetching metadata for all topics from broker localhost:9092
2025/05/13 18:26:30 Connected to broker at localhost:9092 (unregistered)
2025/05/13 18:26:30 client/metadata got error from broker -1 while fetching metadata: EOF
2025/05/13 18:26:30 Closed connection to broker localhost:9092
2025/05/13 18:26:30 client/metadata no available broker to send metadata request to
2025/05/13 18:26:30 client/brokers resurrecting 1 dead seed brokers
2025/05/13 18:26:30 Closing Client
```
</details>

The culprit being simply that:
1. Sarama chooses request versions solely according to the provided
`config.Version`, [even though it sends an
ApiVersionsRequest](https://github.com/IBM/sarama/blob/43f8559f9dc49d7bc46f81adec99aed43d423bf8/broker.go#L189-L201)
4. [MetadataRequest uses versions 8-9-10 for Kafka versions >=
v2.4.0.0](https://github.com/IBM/sarama/blob/43f8559f9dc49d7bc46f81adec99aed43d423bf8/metadata_request.go#L26-L29)
5. [Redpanda only supports versions 0 to
8](https://github.com/redpanda-data/redpanda/blob/bee4479bf54ae2d9af54b07b1203179791b0f166/src/v/kafka/server/handlers/metadata.h#L28),
and it correctly advertises it

</details>

---------

Signed-off-by: Giorgio Pellero <[email protected]>