Allow configuration of zookeeper cluster configs via values.yaml

[chaicesan]

As it stands we can't configure the lower level zookeeper cluster properties (e.g. zoo.cfg) via the solr-operator. I realised this recently when I was debugging one of our services and decided it's worth changing some zookeeper configs but there is no access to them. Specifically I am interested in these properties.

How I envision it working (give or take)

values.yaml

...
zookeeper:
    properties:
        initLimit: 10
        maxClientCnxns: 1000
        syncLimit: 5
        tickTime: 2000
...

If there are any questions then feel free to let me know.