Convert DataEntry to a dataclass

[major]

This simplifies the DataEntry class a bit and allows us to have a really handy __repr__ output whenever we need to print out the contents of the class.

Also, this fixes a mypy issue where content is recast from a string to a dictionary when json.loads() reads it.

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.01% :tada:

Comparison is base (b07c877) 92.10% compared to head (8187aaf) 92.11%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #691 +/- ## ========================================== + Coverage 92.10% 92.11% +0.01% ========================================== Files 9 9 Lines 557 558 +1 Branches 126 127 +1 ========================================== + Hits 513 514 +1 Misses 23 23 Partials 21 21 ``` | [Files Changed](https://app.codecov.io/gh/redhatcloudx/transformer/pull/691?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=redhatcloudx) | Coverage Δ | | |---|---|---| | [src/cloudimagedirectory/connection/connection.py](https://app.codecov.io/gh/redhatcloudx/transformer/pull/691?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=redhatcloudx#diff-c3JjL2Nsb3VkaW1hZ2VkaXJlY3RvcnkvY29ubmVjdGlvbi9jb25uZWN0aW9uLnB5) | `90.62% <100.00%> (+0.14%)` | :arrow_up: |

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