Add support for table comments

[drwl]

This PR makes the following changes:

• Adds support for table comments
• Adds 2 new options keys: with_column_comments and with_table_comments
• Checks for with_comment: true, with_column_comments: true to add column comments
• Checks for with_comment: true, with_table_comments: true to add table comments
• Changes Options#load_defaults, it defaults with_column_comments and with_table_comments to use the value set in with_comment if not previously set

[drwl]

Credit goes to @suzunedev from ctran/annotate_models#987 for PR inspiration. Addresses ctran/annotate_models#917.