SQL: various improvements and fix if/case/loop/end detection with SQL (Oracle)

Summary:
Previously, the variables prefixed by if / case / loop / end are a mix of keywords and normal text.

Improvements:

• Categorization of "Keywords" to "Operator Keyword" and "ControlFlow".
• Removes duplicate keywords in "functions" and "keywords" list.
• Some elements of the keywords list are moved to the functions list.
• Adds SQL functions.
• Removes symbols from Keyword list.

Reviewers: Framework: Syntax Highlighting, dhaumann, cullmann

Reviewed By: Framework: Syntax Highlighting, dhaumann, cullmann

Subscribers: kwrite-devel, kde-frameworks-devel, cullmann, rkflx

Tags: Frameworks, Kate

Differential Revision: https://phabricator.kde.org/D11470