Fix media bar button items

[kean]

Changes

• Revert the change that introduces button groups, and use simple rightBarButtonItems
• Update "add" button to use standard UIBarButtonItem

This fixes and issue where the "Add" button is not visible under certain scenarios.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	29262
	Version	PR #24900
	Bundle ID	com.jetpack.alpha
	Commit	5e5de0e
	Installation URL	32p7fgsaqc1u8

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	29262
	Version	PR #24900
	Bundle ID	org.wordpress.alpha
	Commit	5e5de0e
	Installation URL	7jc8c6cocd3vg

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[jkmassel]

Tested on a 13 mini simulator with Display Zoom on and off.

Both looked fine, so I think this is good to go.