v2 / review and unify column type translation

[sio4]

It seems like there are some reasonable open issues regarding the column type translation from Fizz's to database's.

some findings are:

• First, there is no policy for supported database engine version which is very important
• Also, the purpose of colType() could be slightly confusing
• in many cases, timestamp is just treated as datetime
• only PostgreSQL's datetime has a timezone (but timestamp it not)
• time is treated as datetime which should not be
• date is treated as numeric in SQLite3
• float and decimal are treated as the same (decimal) in most dialects
• and most importantly, have no document for them

Related open issues and PRs (at this moment):

• Support timestamp column type. #48
• Datetime, timestamp, time should support fraction precision #89 and add datetime precision for mysql #90
• Customize generated PostgreSQL created_at and updated_at columns to use timestamptz #106
• Provide Reference Documentation for DDL #66

Also, related issues/PRs on the other modules:

• pop should save created_at and updated_at fields in UTC pop#23
• fizz: define timestamp column types with a timezone pop#25
• timezone automatically appended while reading a timestamp with tz value from postgres pop#595
• setting a time zone for default time stamps pop#753
• Creating timestamp fields instead of time type for postgres pop#687

Old issues/PRs related to this:

• Adding common types from attr #27
• Support float precision fixes #8 #36
• added support of exact numeric data values #57
• switch to timezone aware timestamps #50
• 5a6606f7934c36 - made time datetime
• abae1e934d6182 - timestamp as timestamp for MySQL
• ca8e206c781587 - revert it back

Other issues about an ID field which is restricted to be int or UUID

• Postgres translator does not allow "text" value to be set as a Primary key #64
• Can't call Create(...) using types other than int, int64, UUID or string for primary key pop#605 maybe it should be in pop but need to be considered.

Date type definitions:

• SQLite3: https://www.sqlite.org/datatype3.html
• MySQL: https://dev.mysql.com/doc/refman/8.0/en/data-types.html (current)
• MySQL: https://dev.mysql.com/doc/refman/5.7/en/data-types.html (oldest supported)
• MariaDB: https://mariadb.com/kb/en/data-types/
• MS SQL: https://docs.microsoft.com/sql/t-sql/data-types/data-types-transact-sql?view=sql-server-ver15 (current)
• MS SQL: https://docs.microsoft.com/sql/t-sql/data-types/data-types-transact-sql?view=sql-server-2017 (oldest supported)
• PostgreSQL: https://www.postgresql.org/docs/current/datatype.html (current)
• PostgreSQL: https://www.postgresql.org/docs/10/datatype.html (oldest supported)
• Cockroach: https://www.cockroachlabs.com/docs/stable/data-types.html (current)
• Cockroach: https://www.cockroachlabs.com/docs/v21.1/data-types (oldest supported)

Release/Support/Lifecycle policy for database engines:

• https://www.mysql.com/support/supportedplatforms/database.html
• https://docs.microsoft.com/lifecycle/products/?products=sql-server
• https://www.postgresql.org/support/versioning/
• https://www.cockroachlabs.com/docs/releases/release-support-policy