Rethink column name determination in SQL source

[ckittl]

https://github.com/ie3-institute/PowerSystemDataModel/blob/be6b20b7b8bdbb93b13d5f24c1c7c9f02032e011/src/main/java/edu/ie3/datamodel/io/source/sql/SqlDataSource.java#L52-L76

The SQL sources use a method, that queries the given column names in a given table and tries to find a "match" based on a given "search string".

I feels like this method is a bit error prone and imperformant. Rethink, if this method really is useful or if we can switch over to fixed and defined column names.

[sebastian-peter]

This is somewhat related to #515. Yes, we can think about this. Trade-off is the same as with csv sources, column names then have to be exact.

[sebastian-peter]

I think this is a great opportunity to introduce NamingConvention to all relevant sources.