Remove xblockutils package

[farhan]

Parent ticket: openedx/axim-engineering#915

This repository is using the xblock-utils package which has been deprecated and migrated to within the xblock package.

In this ticket, we will:

Tasks

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1. Make sure the repository is using xblock version 1.8.1 or above. Upgrade the version if required, preferably via the make upgrade command.
2. Remove the xblock-utils package
3. Find and replace all the xblockutils.* imports with xblock.utils.*
4. Make sure all the test cases are passing
5. Test the xblock

[farhan]

PR: #417

[feanil]

PR has been merged and published to PyPI