Sybase TEXT throws exception in count column validation

**Describe the bug**
Sybase TEXT throws exception in count column validation:
```
sqlalchemy.exc.DataError: (pyodbc.DataError) ('22018', '[22018] [FreeTDS][SQL Server]The COUNT AGGREGATE operation cannot take a TEXT datatype as an argument.\n (409) (SQLExecDirectW)')
```

**What version of DVT are you using?**
8.4.0

**What type of connections are you using for source and target?**
Sybase

**Expected behavior**
We need to change DVT to follow the same steps as Oracle CLOB. i.e.:

1. Implement `raw_column_metadata` in `ibis_sybase/__init__.py`
2. Add an `_is_sybase_text` method to `config_manager.py`, use `is_oracle_lob` as a template
3. Add a call to `_is_sybase_text` where we use `is_oracle_lob` below:

```
if all(
_ in ["string", "!string", "json", "!json"]
for _ in [column_type, target_column_type]
):
# These data types are aggregated using their lengths, except for count().
if agg_type == "count":
# Oracle LOBs and Sybase TEXT need a length() before the count().
return (self._is_oracle_lob(source_column, target_column) or self._is_sybase_lob(source_column, target_column))
else:
return True
```

Search for "issue-1675" in the repo when working on this issue.