Summary of the changes / Why this is an improvement

Adding a view for User Defined Functions helps to manage and replace UDFs within CrateDB.
Before one would need to manually manage UDFs outside of CrateDB and/or remember queries like.

SELECT *
FROM information_schema.routines
WHERE routine_type = 'FUNCTION';

to check which UDFs exist within CrateDB

forked from Views-view / section

Open To-Dos:

• Find or Create a suitable icon for sidebar
• Find a solution to translate internal data types like integer_array to ARRAY(INTEGER)
• Finish Create or Replace functionality
• Add correct translations (i18n)
• General cleanup (As this was derived from the views view)

closes #734

Checklist

• CLA is signed