Adding sidecar feature to zookeeper-operator

[adapured]

Change log description

Adding sidecar features to zookeeper-operator

Purpose of the change

Fixes #345
Integrate. and enable the Sidecars with zookeeper-operator

What the code does

Enable and. configure volumes and environment variables required for sidecars.

How to verify it

1.Helm lint.
2.Update the .Values with Any Sidecar containers.
3.By adding required additional volumes and Environment variables.
4.helm template.

[adapured]

@anishakj forked from pravega/zookeeper-operator repo and fixed conflicts. Closed the old PR(#341)

[codecov-commenter]

Codecov Report

Merging #344 (2cf0ed2) into master (b087a7f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #344   +/-   ##
=======================================
  Coverage   84.52%   84.52%           
=======================================
  Files          11       11           
  Lines        1376     1376           
=======================================
  Hits         1163     1163           
  Misses        140      140           
  Partials       73       73           

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[SrishT]

LGTM