List Parameters of an Instance

[kensipe]

Details provided by @mpereira in #1029
I'll summarize here...

What would you like to be added:
That PR #1029 is to list parameters of an operator for an user (that might want to install an operator). Which is a day 1 operation.

What is being requested by @mpereira is the ability to get parameters of an instances. This is valuable
for a day 2 operation... the operator is installed, the user may want to

1. confirm a parameter
2. change it but have a reference
3. want to upgrade the operator but needs existing information.

The needs for operators and instances are also quite different. for an operator you may need to specify a version while an instance has a defined version. For an instance you may want to define a namespace, where for an operator that makes no sense. While the output format may be close to the same these are very different things.

Here are the options @mpereira provided:

kubectl kudo get cassandra \
    --namespace=cassandra-ns \
    --all-parameters
Name          Value          Default          Required          Description
<...>         <...>          <...>            <...>             <...>

$ kubectl kudo get cassandra \
    --namespace=cassandra-ns \
    --parameter=NODE_COUNT
Name          Value          Default          Required          Description
NODE_COUNT    <...>          <...>            <...>             <...>

The flags may need to be rethought out as well. --required makes a lot of sense for an day 1 requirement for a param that is required but doesn't have a default. day 2 this may not make sense.