**Describe the bug**
According to https://jira.percona.com/browse/PT-1945 and https://github.com/ClickHouse/ClickHouse/pull/21367

**Does it reproduce on a recent release?**
yep

**How to reproduce**
- define `mysql_port`
- run following SQL queries via MySQL client
```
mysql> SELECT DATABASE(), CONNECTION_ID(), VERSION()/*!50038 , @@hostname*/;
ERROR 46 (00000): Code: 46, e.displayText() = DB::Exception: Unknown function CONNECTION_ID. Maybe you meant: ['connection_id','connectionID']: While processing DATABASE(), CONNECTION_ID(), VERSION() (version 21.3.2.5 (official build))
mysql> SELECT DATABASE(), connection_id(), VERSION()/*!50038 , @@hostname*/;
ERROR 46 (00000): Code: 46, e.displayText() = DB::Exception: Unknown function VERSION. Maybe you meant: ['version']: While processing DATABASE(), connection_id(), VERSION() (version 21.3.2.5 (official build))
mysql> SELECT DATABASE(), connection_id(), version()/*!50038 , @@hostname*/;
+------------+-----------------+-----------+
| DATABASE() | connection_id() | version() |
+------------+-----------------+-----------+
| default    |               0 | 21.3.3.14  |
+------------+-----------------+-----------+
```

**Expected behavior**
VERSION() and CONNECTION_ID() aliases should work ;)

#include <Functions/IFunctionImpl.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypeString.h>
#include <Core/Field.h>
#if !defined(ARCADIA_BUILD)
#    include <Common/config_version.h>
#endif
namespace DB
{
/** version() - returns the current version as a string.
  */
class FunctionVersion : public IFunction
{
public:
    static constexpr auto name = "version";
    static FunctionPtr create(const Context &)