Fix search for RSS feeds in Reader

[kean]

• Add meta=feed parameter to the search endpoint and update parsing to support .feed data. Note: I accidentally added this change to a commit in 2c8a7c5 by amending it. It already got merged.
• Update ReaderFeedCell to use FaviconService when other icons are not available
• Update FaviconService to support apple-touch-icon-precomposed (an old HTML meta key still used on some sites)

Before / After

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 26.5 ❄️. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

	1 Message
📖	This PR contains changes to RELEASE-NOTES.txt. Note that these changes won't affect the final version of the release notes as this version is in code freeze. Please, get in touch with a release manager if you want to update the final release notes.

Generated by 🚫 Danger

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
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

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	App Name	Jetpack
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	Build Number	29954
	Version	PR #25023
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	Commit	2a452ac
	Installation URL	0g8230ascrrm0

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📲 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	29954
	Version	PR #25023
	Bundle ID	org.wordpress.alpha
	Commit	2a452ac
	Installation URL	76nafb0ngs898

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