Cater for column name mismatches across systems

Columns names occasionally differ between systems. For example when copying data from a transactional system to a data warehouse we may choose to give id columns a more descriptive name.

It would be good if this could be automated in some way.

- If DVT already assumed the columns are in the correct order then maybe it should honour the names
- If there is no expected order then perhaps we need a `--column-name-mappings` option to map the names
- This needs to work for primary keys too.

**Test case**
Oracle table:
```
create table dvt_test.tab1_a
(id number(5),col_data varchar2(30));
```

PostgreSQL table:
```
create table dvt_test.tab1_a
(tab_id int,col_data varchar(30));
```

DVT command:
```
data-validation validate column -sc=ora_local -tc=pg_local -tbls=dvt_test.tab1_a --count="*" --sum="*"
...
File "/path/github/professional-services-data-validator/data_validation/config_manager.py", line 1059, in build_config_column_aggregates
casefold_target_columns[column]
~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
KeyError: 'id'
```

**What version of DVT are you using?**
8.1.1

**Describe the solution you'd like**
A clear and concise description of what you want to happen.

**Describe alternatives you've considered**
Storing the validations to YAML files and then editing and correcting manually.

**How are you executing DVT?**
CLI commands

**Additional context**
Add any other context or screenshots about the feature request here.