Replace xblock.fragment with web_fragments.fragment

[KristinAoki]

As of 2024-02-26, xblock.fragment has been removed. It has been deprecated since 2018. If courses use this xblock with the newest version of edx-platform the course will not be able to load.

Please update activetable.py L12

[samuelallan72]

@KristinAoki thanks for your report, and sorry for the delay in responding. We'll plan to take a look soon.

Internal ticket: BB-10568 | BB-11013

[kaustavb12]

@KristinAoki Due to low usage of this XBlock and since we did not have enough budget/bandwidth to continue to maintain it, we have decided to archive this repo. We are therefore closing this issue now.