Insert complex types with cursor.execute + client-side binding

[sitingren]

Related to #469.

• [use_prepared_statements=False only] Add default mappings from python types (list, set, dict) to SQL literals (ARRAY, SET, ROW)
• Improve error message and debug logging

[Alexxz]

Could someone explain please on how important were the following changes of this MR?

            if parameters and ':' not in operation:
                raise ValueError(f'Invalid SQL: {operation}'
                    "\nHINT: When argument 'parameters' is a dict, variables in SQL should be specified with named (:name) placeholders."
                    " If you use a dict to represent the value of a ROW type column, enclose the dict with brackets('[]') to construct a list.")

Before these changes came into project I could use bag of named parameters as good placeholders for SQL no matter if they are used in the specific query or not.
Something like:

params = dict(date=current_date, password='XXX')
sqls = [
    'TRUNCATE TABLE tab1',
    'CONNECT TO VERTICA ... :password',
    'INSERT INTO tab1 SELECT ... WHERE dt = :date',
]
for sql in sqls:
    v.execute(sql, params)

This fails on TRUNCATE TABLE operation. It looks my approach is forbidden at all. Is my approach bad? Usage of named parameters usually assumes that these parameters are all optionally used.

[sitingren]

@Alexxz You can set environment variable VERTICA_PYTHON_IGNORE_NAMED_PARAMETER_CHECK to 1 to get rid of the exception.