Make BP custom functions available through BlazeCriteriaBuilder

[jwgmeligmeyling]

The CriteriaBuilder has some utility methods to create function expressions. BlazeCriteriaBuilder could extend this with the custom functions Blaze Persistence provides. My personal candidate list:

• Group concat aggregation
• Custom builder for window expressions, and methods for the WINDOW_SUM, WINDOW_MAX, WINDOW_AVG, WINDOW_MIN, WINDOW_COUNT,WINDOW_GROUP_CONCAT, WINDOW_EVERY and WINDOW_OR_AGG, ROW_NUMBER, RANK, DENSE_RANK, PERCENT_RANK, CUME_DIST, NTILE, LEAD, LAG, FIRST_VALUE, LAST_VALUE, NTH_VALUE

Candidates that are perhaps too specific / type bound and are better suited for a dedicated utility API

• Date trunc functions
• Date add functions
• Date extract functions

I believe LEAST, GREATEST , CAST are already provided. Not sure what else makes sense to include.

Description

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[beikov]

https://github.com/Blazebit/blaze-persistence/pull/1383 will add support for most of these functions. The only ones left now are:

• Date trunc functions
• Date add functions
• Date extract functions