fix(blockdeviceclaim-build-file): Add new build function to add any BDC selectors

[Ab-hishek]

Signed-off-by: Abhishek Agarwal abhishek.agarwal@mayadata.io

Why is this PR required? What issue does it fix?: Adds a new function to add Selectors to BDC. Currently only one fixed selector can be added to the BDC and that is "openebs.io/block-device-tag".

What this PR does?: The function added will allow to add any number of selector labels to the BDC by passing a map of string key and values.

Does this PR require any upgrade changes?: No.

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

Any additional information for your reviewer? :

Checklist:

• [ ] Fixes #
• [x] PR Title follows the convention of <type>(<scope>): <subject>
• [ ] Has the change log section been updated?
• [x] 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:

[kmova]

@Ab-hishek -- can you push this change into the openebs/api as well here: https://github.com/openebs/api/blob/master/pkg/apis/openebs.io/v1alpha1/blockdeviceclaimbuilder.go