GEOT-4229 fix join of more than two tables

Signed-off-by: r0bb3n <r0bb3n@gmx.de>
Merge branch '8.x' of https://github.com/r0bb3n/geotools into 8.x

Conflicts:
	modules/library/jdbc/src/main/java/org/geotools/jdbc/JDBCJoiningFeatureReader.java
	modules/library/jdbc/src/test/java/org/geotools/jdbc/JDBCJoinTest.java