[TASK] Doctrine: Add support for aggregate SQL functions

This patch extends the SQL Expressionbuilder with support for generating
expressions for MIN, MAX, AVG, SUM and COUNT aggregate functions, as
well as adding support for selecting literal (unquoted) SQL expressions
with the QueryBuilder using ->selectLiteral() and ->addSelectLiteral().

Releases: master
Resolves: #75822
Change-Id: Id1043ec8a60be1e6d3c273278a776e92bb8c973e
Reviewed-on: https://review.typo3.org/47826


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>