[client-v2] fixed number conversion in reader

[chernser]

Summary

This PR implement conversion between different number types. Today client API (readers) allow to get column value only in the type it is defined in a DB. It is very inconvenient because requires to follow schema very strictly. So this PR relaxes this rule and lets to:

• read a value of a number column as number with bigger range than it is defined in DB- 'int8' as int, int32 as long.
• read a value of a number column as number with smaller range than it is defined in DB if actual value fits it - int32 value like 1000 can be read as short but not as byte.

Closes: #1852

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

[sonarcloud]

Quality Gate failed

Failed conditions
49.7% Coverage on New Code (required ≥ 80%)

See analysis details on SonarCloud

[mzitnik]

Can we tell if there any performance impact from this change?

[chernser]

@mzitnik I may not tell exact numbers - will try running benchmark tests.