oracledb thin client - support locale specific date and number conversion

Currently there is no native support for the python oracledb module, so this issue occurs when using "connect using custom params" mode (see #173 for connection example).
There is a problem if the test data used in Robot Framework has some regional format different from the Oracle DB.
For example, with decimal/float number and dates:
- The standard English Oracle format for a decimal number is point-based - e.g. `123.45`.
- But in some other languages/regions (e.g. in Germany) the comma-based format is used - `123,45`.

So before I save some local values to the database or compare them with the database values, there is some conversion to be done.
**Currently it has to performed manually**.
### Maybe there is a better way?

The thin mode of the oracledb client doesn't support Oracle Globalization variables (see the full comparison between thin and thick clients [here](https://python-oracledb.readthedocs.io/en/latest/user_guide/appendix_a.html#featuresummary)).
So they advice to use the python globalization support - and provide an [example](https://python-oracledb.readthedocs.io/en/latest/user_guide/globalization.html#thin-mode-locale-aware-number-and-date-conversions).

Also I'm not sure, but maybe this issue is relevant also for other databases?

Start with the custom-params connection mode and the connection example in issue #173, then read the linked python-oracledb thin-mode globalization example. Define how locale-aware date and number conversion should work for Robot Framework test data, and clarify whether the scope includes databases beyond Oracle.

Written by the indexing model from the issue text.