Improve 18c support

[joschug]

This fixes #204, #207 and probably #200.

• Resolve type synonyms
• Support cross-schema type references
• Added support for package types declared as %ROWTYPE
• Added support for %ROWTYPE as procedure parameter
• Exclude hidden columns from table types
• Remap TIMESTAMP(n) WITH LOCAL TIMEZONE to TIMESTAMP WITH LOCAL TIMEZONE
• Remap PL/SQL PLS/BINARY INTEGER to PLS_INTEGER/BINARY_INTEGER

[yahonda]

Could you please break this pull request into smaller pieces?

[Faq]

Using this for a year with Rails 5.2 and 18c, now upgraded with Rails 7, still works.