Support for InfluxQL

Nobody has claimed this yet.

__Proposal:__
According to [this document](https://docs.influxdata.com/influxdb/v2.7/query-data/influxql/). The influxdb still supports the influx Query Language (QL).

__Current behavior:__
Currently using a query which has QL syntax ends with error:
`error @1:1-1:7: undefined identifier select`

__Desired behavior:__
There is a way to run influx Query Language with [this client](https://github.com/influxdata/influxdb-client-csharp). If this is not supported, it should be written explicitly in the documentation that this feature is not supported.

__Alternatives considered:__
- Rewriting all the QL-queries into flux which cause additional effort
- Writing own client to support the Query Language

__Use case:__
Existing application used in production was implemented using Query Language syntax. After upgrading the database from version 1.x to the newest 2.x it is not possible to use the [client](https://github.com/influxdata/influxdb-client-csharp) with queries written in Query Language

Start with the linked InfluxQL documentation and the client’s query API, which are the only implementation entry points identified in the issue. Determine whether InfluxQL should be supported or explicitly documented as unsupported; done means one of those outcomes is clearly established for users.

Written by the indexing model from the issue text.