Add charset option

[alfawal]

Our team added i18n support to some fields by converting them to JSON fields and adding language key-value pairs.

Upon replicating to ClickHouse, we encountered an issue where the Arabic translations are being shown with unicode escaped format. Showing like this:

Our MySQL charset settings:

SHOW VARIABLES LIKE 'character_set%';
SHOW VARIABLES LIKE 'collation%';
SHOW SESSION VARIABLES LIKE 'character_set%';

-- Output:
character_set_client	utf8mb4
character_set_connection	utf8mb4
character_set_database	utf8mb4
character_set_filesystem	binary
character_set_results	utf8mb4
character_set_server	utf8mb4
character_set_system	utf8mb3
character_sets_dir	/usr/share/mysql/charsets/

So I tried changing the replicator's charset for the settings, API and binlog, and it worked.

However, I wasn't able to reproduce the issue (with the same docker containers setup). Hence, the test added in this PR isn't verified.