build scripts: raise Java version in module intellij.tools.jps.antTasks to Java 8
build scripts: raise Java version in module intellij.tools.jps.antTasks to Java 8

Classes from this module are used to build IntelliJ-based IDEs only, and these build scripts require Java 8 anyway. So there is no sense to keep compatibility with older Java versions here. Also the module uses Ant library which class-files aren't compatible with older Java versions so this cause compilation errors when the code is compiled by javac from JDK 11.

GitOrigin-RevId: d4fd048accf9c44a00e87c2c53981073ba2bec88
allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community