feat: Add dbt_tags__opt_in_default_naming_config to disable env management

[bkimjin]

resolves #19

This is a:

• documentation update
• bug fix with no breaking changes
• new functionality
• a breaking change

All pull requests from community contributors should target the main branch (default).

Description & motivation

Add variable dbt_tags__opt_in_default_naming_config to use dbt_tags__database and dbt_tags__schema to disable the env management from dbt.

Checklist

• This code is associated with an Issue which has been triaged and accepted for development
• I have verified that these changes work locally on the following warehouses (Note: it's okay if you do not have access to all warehouses, this helps us understand what has been covered)
  • Snowflake
• I have updated the README.md (if applicable)
• I have added tests & descriptions to my models (and macros if applicable)

[il-dat]

Thanks @bkimjin , it will be released in v1.3 soon