refractor: Wrap NewK8sClient for error handling in client init

[Abhishek-kumar09]

Signed-off-by: Abhishek-kumar09 abhimait1909@gmail.com In the case of wrong kubeconfig, or no kubeconfig or no kubernetes the client initialisation throws error which are not handled by the current code at multiple places resulting in panic by CLI.

• [x] Wrapped the client initialization with error-handling implicitly.
• [x] Made namespace as optional argument, so that if we don't want to provide namespace and want to search in all namespaces we can omit passing empty string in functional arguments

[codecov-commenter]

Codecov Report

Merging #120 (e39f511) into develop (b6c29c2) will increase coverage by 2.63%. The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop     #120      +/-   ##
===========================================
+ Coverage    67.08%   69.72%   +2.63%     
===========================================
  Files           24       24              
  Lines         1820     1820              
===========================================
+ Hits          1221     1269      +48     
+ Misses         590      542      -48     
  Partials         9        9              

Impacted Files	Coverage Δ
pkg/blockdevice/blockdevice.go	73.07% <0.00%> (ø)
pkg/cluster-info/cluster-info.go	95.37% <0.00%> (ø)
pkg/persistentvolumeclaim/debug.go	0.00% <0.00%> (ø)
pkg/persistentvolumeclaim/persistentvolumeclaim.go	0.00% <0.00%> (ø)
pkg/storage/storage.go	0.00% <0.00%> (ø)
pkg/volume/volume.go	13.04% <0.00%> (ø)
pkg/util/util.go	51.04% <0.00%> (ø)
pkg/volume/local_hostpath.go	100.00% <0.00%> (+100.00%)	:arrow_up:

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