fix(conn): ensure ReadTimeout applies to each conn.Read

[GeorgeMac]

Summary

Fixes #1607

This PR addresses the issue of ReadTimeout currently only applying to the first block returned on a query to ClickHouse.

For the Changelog:

Fix `ReadTimeout` so that it applies to each call to `conn.Read` not just the first read block

The first change in this PR introduces lib/proto updates to support some of the missing client encoding and server decoding functions for CH packets.
This was so that I could implement a fake CH server where we can define our own handlers:
https://github.com/GeorgeMac/clickhouse-go/blob/37404af3d6637594d79bf3345a20970ddba01c31/lib/testing/server.go#L57-L85

Then I used this fake server in a couple unit tests. The first a simple happy path SELECT 1, mostly to ensure that the fake server was working as expected alongside the client.

The second is the case which demonstrates the problem in the issue.
When the test suite is run with a timeout before the fix in 299fe0c:

=== RUN   TestConn_Query_ReadTimeout
time=2025-07-20T08:48:50.671+01:00 level=DEBUG msg="Packet type" type=0
time=2025-07-20T08:48:50.671+01:00 level=DEBUG msg="Handling handshake" handshake="clickhouse-go/2.37.2 (lv:go/1.24.4; os:darwin) 2.37.0" auth="{database: username:default password:}"
time=2025-07-20T08:48:50.671+01:00 level=DEBUG msg="Packet type" type=4
time=2025-07-20T08:48:50.671+01:00 level=DEBUG msg="Packet type" type=1
time=2025-07-20T08:48:50.671+01:00 level=DEBUG msg="Handling query" query="&{ID: ClientName:clickhouse-go/2.37.2 (lv:go/1.24.4; os:darwin) ClientVersion:2.37.0 ClientTCPProtocolVersion:54460 Span:{traceID:[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] spanID:[0 0 0 0 0 0 0 0] traceFlags:0 traceState:{list:[]} remote:false} Body:SELECT 1 QuotaKey: Settings:[] Parameters:[] Compression:false InitialUser: InitialAddress:[::1]:53128}" blocks=[]
=== RUN   TestConn_Query_ReadTimeout/first_row_is_returned
=== RUN   TestConn_Query_ReadTimeout/second_row_timeout
panic: test timed out after 10s
        running tests:
                TestConn_Query_ReadTimeout (10s)
                TestConn_Query_ReadTimeout/second_row_timeout (10s)

Which nicely demonstrates in the panic output where the client blocks on rows.Next():

goroutine 5 [select]:
github.com/ClickHouse/clickhouse-go/v2.(*rows).Next(0x1400001e120)
        /Users/georgemacrorie/github/ClickHouse/clickhouse-go/clickhouse_rows.go:52 +0x118
github.com/ClickHouse/clickhouse-go/v2.TestConn_Query_ReadTimeout.func4(0x14000003340)
        /Users/georgemacrorie/github/ClickHouse/clickhouse-go/conn_test.go:119 +0x34
testing.tRunner(0x14000003340, 0x1400000c060)
        /opt/homebrew/Cellar/go/1.24.4/libexec/src/testing/testing.go:1792 +0xe4
created by testing.(*T).Run in goroutine 38
        /opt/homebrew/Cellar/go/1.24.4/libexec/src/testing/testing.go:1851 +0x374
FAIL    github.com/ClickHouse/clickhouse-go/v2  10.349s
FAIL

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials

[GeorgeMac]

Note for the reviewer:

This particular context driven deadline is now being checked on each read down in the net stack (it is not being removed after first read) this test became unstable. I tweaked the timeout running the tests with -count 10 until I could get something consistent. Three seconds seemed enough to process all of the response.