Fix site icon selection keyboard issue

[guarani]

Fixes #21520

The solution I used here is to dismiss the picker (which closes the keyboard) before opening the Resize & Crop screen. I guess many users who change their site icons have run into this bug because they often have lots of images, and the Photos search (which triggers the keyboard) is very useful for finding the image they're looking for.

The Resize & Crop screen is presented over the PHPickerViewController. This is an uncommon way of doing things because the PHPickerViewController is left open after the user selects their media. In other parts of the app where the picker is used, it's dismissed immediately after selection (e.g. uploading to site media, image block, profile photo picker, etc).

Presumably, leaving the picker open saves users time if they want to choose a new image on the Resize & Crop screen. By leaving the picker open, users can move back and forth between the picker and the Resize & Crop screen with little friction.

All the known ways of closing the keyboard don't work with the PHPickerViewController's keyboard, as noted in https://stackoverflow.com/questions/76738328/dismiss-keyboard-for-phpickerviewcontroller-not-working.

With this PR, this is how choosing a site icon works now (see the video at #21520 (comment) for how it worked before):

RPReplay_Final1715283502.MP4

To test

1. Log in to the Jetpack app
2. Tap the site icon on the My Site screen
3. Tap "Choose from Device"
4. In the image picker, make the keyboard appear by doing a search (⚠️ not available on simulators)
5. Choose an image
6. Notice the keyboard is dismissed along with the picker (previously the picker remained open)
7. Complete the flow through the Resize & Crop screen

Regression Notes

1. Potential unintended areas of impact

The could inadvertently introduce regressions in the the site icon selection flow

9. What I did to test those areas of impact (or what existing automated tests I relied on)

Manual testing

10. What automated tests I added (or what prevented me from doing so)

Since this flow involves the photo picker, I don't think tests are suitable.

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Testing checklist (left unchecked the ones that seem irrelevant for this PR):

• WordPress.com sites and self-hosted Jetpack sites.
• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• VoiceOver.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• iPhone and iPad.
• Multi-tasking: Split view and Slide over. (iPad)

[wpmobilebot]

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

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr23181-ae58e5a
	Version	24.8
	Bundle ID	org.wordpress.alpha
	Commit	ae58e5a
	App Center Build	WPiOS - One-Offs #9862

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[wpmobilebot]

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

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr23181-ae58e5a
	Version	24.8
	Bundle ID	com.jetpack.alpha
	Commit	ae58e5a
	App Center Build	jetpack-installable-builds #8910

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[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 24.9. This milestone is due in less than 4 days. Please make sure to get it merged by then or assign it to a milestone with a later deadline.

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[guarani]

I just saw a previous PR on this: #21564 (comment), so I'll close this and move the discussion there.