kiwix-serve : provide a solution to customize cache settings #738
Description
openzim/libzim#950 released in libzim 9.3.0 removed the support for configuration of cache behavior with ZIM_CLUSTERCACHE, ZIM_DIRENTCACHE and ZIM_DIRENTLOOKUPCACHE environment variables, since it is now possible to do so via CPP API.
kiwix-serve should be adapted to make these configurations available again.
It is not extremely urgent because we do not use these settings on our libraries (library.kiwix.org, ...) but we are pretty sure some of our users use these settings on their hotspots for instance. And we might want to do so as well.
Note this will be only a temporary move since libzim 10 will remove these settings in favor of a global memory usage setting.