feat (provisioner-localpv): Merge CAS config from PersistentVolumeClaim

[nobiit]

Pull Request template

Why is this PR required? What issue does it fix?:
Allows users to filter the type of storage they want right from the PVC. Instead of having to create multiple StorageClass types for infrequent volumes

What this PR does?:
Merge CAS from PersistentVolumeClaim and StorageClass

Does this PR require any upgrade changes?:
No

If the changes in this PR are manually verified, list down the scenarios covered::

• PVC has annotations attribute cas.openebs.io/config and it is included in BlockDeviceClaim

Any additional information for your reviewer? :
Mention if this PR is part of any design or a continuation of previous PRs

Checklist:

• Fixes #
• PR Title follows the convention of <type>(<scope>): <subject>
• Has the change log section been updated?
• Commit has unit tests
• Commit has integration tests
• (Optional) Are upgrade changes included in this PR? If not, mention the issue/PR to track:
• (Optional) If documentation changes are required, which issue on https://github.com/openebs/openebs-docs is used to track them:

[codecov-commenter]

Codecov Report

Merging #144 (fd98f1a) into develop (e797585) will decrease coverage by 0.09%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop     #144      +/-   ##
===========================================
- Coverage    38.00%   37.91%   -0.10%     
===========================================
  Files           36       36              
  Lines         3365     3373       +8     
===========================================
  Hits          1279     1279              
- Misses        2004     2012       +8     
  Partials        82       82              

Impacted Files	Coverage Δ
cmd/provisioner-localpv/app/config.go	16.31% <0.00%> (-0.99%)	⬇️

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[niladrih]

@nobiit -- Thank you for your contribution! I have few comments on your contribution.
Volume-level configuration should take precedence over StorageClass configuration, if the same configuration keys exist for both. PVC config should be merged into the PV config before the StorageClass config is merged.

Also, the key values from the first argument in the cast.MergeConfig() takes precedence over the ones in the second.
PTAL here https://github.com/openebs/dynamic-nfs-provisioner/blob/develop/provisioner/config.go#L118.

[niladrih]

@nobiit -- The change in the above comment, is not required. Let's go with what you've implemented already. On second thought, the config in the SC should take precedence. The SC config is something a cluster admin may want to enforce.

[niladrih]

This change is required, otherwise LGTM.

[niladrih]

Suggested change

	pvConfig = cast.MergeConfig(pvcCASConfig, pvConfig)
	// Config keys which already exist (SC config),
	// will be skipped
	// i.e. SC config will have precedence over PVC config,
	// if both have the same keys
	pvConfig = cast.MergeConfig(pvConfig, pvcCASConfig)

[niladrih]

Closing this PR as these changes have been included in #190.