This PR implements the feature request in #6706

project on list of column types

This allows you to provide a list of types to project on instead of column names, selecting all of the columns of the relation that match any of the provided types.

The implementation of this is likely temporarily, as discussed in the linked request.
Aiming to replace this when we have support for this functionality in core.

DuckDBPyType

I initially thought it was overkill to add a python class to represent our LogicalType, but we have thought of another use for this, so I have opted to add it anyways.

Primitives (defined on duckdb.typing)

• SQLNULL
• BOOLEAN
• TINYINT
• UTINYINT
• SMALLINT
• USMALLINT
• INTEGER
• UINTEGER
• BIGINT
• UBIGINT
• HUGEINT
• UUID
• FLOAT
• DOUBLE
• DATE
• TIMESTAMP
• TIMESTAMP_MS
• TIMESTAMP_NS
• TIMESTAMP_S
• TIME
• TIME_TZ
• TIMESTAMP_TZ
• VARCHAR
• BLOB
• BIT
• INTERVAL

Creation methods

• sqltype(type_str: str)
  alias: type, dtype
  create a type from parsing the type_str, this can also be used for user or extension defined types
• string_type(collation: str = "")
  create VARCHAR type with optional collation
• decimal_type(width: int, scale: int)
  create a DECIMAL type of the given width + scale
• enum_type(name: str, type: DuckDBPyType, values: list)
  create en ENUM type from the 'values' list, cast as type as underlying values
• array_type(type: DuckDBPyType)
  alias: list_type
  create a LIST type of the 'type' as child type
• struct_type(fields: List[DuckDBPyType] | Dict[str, DuckDBPyType])
  alias: row_type
  create a STRUCT type of the given field types (uses default names if given as List)
• map_type(key: DuckDBPyType, value: DuckDBPyType)
  create a MAP type out of the 'key' and 'value' types
  union_type(members: List[DuckDBPyType] | Dict[str, DuckDBPyType])
  create a UNION type of the given member types (similar to STRUCT)

Misc

Can be compared against strings
Converts implicitly from: str, builtins types (str, bool, float etc..), list, dict, {'name', type, ..} dictionary (to STRUCT), numpy builtin types int64, bool_, float32 etc.