ClickHouse: Support for special characters in column names

[Amogh-Bharadwaj]

Avro requires alphanumeric + underscore field names. However Postgres column names do not have the same restriction.

• This PR introduces a map of column names to an Avro compatible encoding of the same. Violating characters are replaced by underscore and the resulting string is suffixed with a serial number.
• This is utilized only for the initial load Avro loading since for CDC the columns will be that of our raw table columns.
• This PR only implements this support for ClickHouse target peers
• It also supports these columns for our normalize inserts by escaping the single quotes in column name argument of the JSONExtract* functions
• Functionally tested and the unprivileged columns E2E test has been adapted to include more columns to test this PR

Fixes #2701

[serprex]

#2701