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).
So they advice to use the python globalization support - and provide an example.

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

先从 issue #173 中的 custom-params 连接模式和连接示例开始，然后阅读链接的 python-oracledb thin-mode 全球化示例。定义 Robot Framework 测试数据应如何进行支持 locale 的日期和数字转换，并明确范围是否包括 Oracle 之外的数据库。