Added activity item for fleetd enrollment with host serial and display name. (#23790)

[getvictor]

22810

(cherry picked from commit 698e9e80fe6971d63c542718436997092fb96d22)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Please upload report for BASE (rc-minor-fleet-v4.60.0@2ca7b28). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...e/cards/ActivityFeed/ActivityItem/ActivityItem.tsx	0.00%	7 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## rc-minor-fleet-v4.60.0 #23926 +/- ## ========================================================= Coverage ? 63.15% ========================================================= Files ? 1559 Lines ? 148136 Branches ? 3788 ========================================================= Hits ? 93552 Misses ? 47190 Partials ? 7394 ``` | [Flag](https://app.codecov.io/gh/fleetdm/fleet/pull/23926/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fleetdm) | Coverage Δ | | |---|---|---| | [frontend](https://app.codecov.io/gh/fleetdm/fleet/pull/23926/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fleetdm) | `52.59% <0.00%> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=fleetdm#carryforward-flags-in-the-pull-request-comment) to find out more.

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[getvictor]

The TestOperatingSystemVulnerabilities/InsertSingleOSVulnerability test fail doesn't seem related to my changes.