Fix innoverio.vscode-dbt-power-user Exasol errors (#78)

The innoverio.vscode-dbt-power-user VScode extension expects all errors
coming from DBT adapters to be raised as DBT errors. The dbt-exasol
adapter was raising Exasol DB errors as pyexasol's QueryError error type
and so this caused problems in the vscode extension.

This commit changes the error to the standard DBT DB error type.

Co-authored-by: Peter Kioko <kioko@grantstreet.com>

dbt/adapters/exasol/connections.py

@@ -263,7 +263,10 @@ def execute(self, query, bindings: Optional[Any] = None):
             for sql in sqls:
                 self.stmt = self.connection.execute(sql)
         else:
-            self.stmt = self.connection.execute(query)
+            try:
+                self.stmt = self.connection.execute(query)
+            except pyexasol.ExaQueryError as e:
+                raise dbt.exceptions.DbtDatabaseError("Exasol Query Error: " + e.message)
         return self
 
     def fetchone(self):