extend testing coverage of `Kread` app on `z:acceptance`

[Jorge-Lopes]

Objective: The existing test of the KREAd application on the z:acceptance test phase was limited to the feature allowing users to mint a new KREAd Character.

The KREAd test coverage should be extended to the same test cases as the ones done for the Smoke Test:

• Alice mints a new Character
• Alice unequips all defaults Items
• Alice sells unequipped Item
• Bob buys an Item on marketplace
• Alice sells a Character
• Bob buys a Character on marketplace

Since the test cases above overlaps with the existing one, the following files should be removed:

• create-kread-item-test.sh
• generate-kread-item-request.mjs

### Tasks
- [x] Identify test cases to implement
- [x] Build test file with new test cases
- [x] Build helper functions
- [x] Remove unnecessary files
- [x] Update z:acceptance test script

[Jorge-Lopes]

This working Item resulted in a discussion opened on Agoric-sdk repo:

https://github.com/Agoric/agoric-sdk/discussions/10218