Filter media types when presenting the Media Picker for Mobile Gutenberg

[twstokes]

Fixes:

• iOS: Image and Video blocks don't filter their media types on Albums view gutenberg-mobile#4371

To test:

Images

1. Ensure at least one image and one video exist in the Photos app and that the WordPress app has appropriate access (configure access to Photos in iOS Settings -> WordPress). It's simplest to allow access to All Photos.
2. Start a new Post and add an Image block
3. Tap "Add Image".
4. Tap "Choose from device".
5. Thumbnails of videos should not be shown
6. Videos should so a count of 0

Videos

1. Ensure at least one image and one video exist in the Photos app and that the WordPress app has appropriate access (configure access to Photos in iOS Settings -> WordPress). It's simplest to allow access to All Photos.
2. Start a new Post and add an Video block
3. Tap "Add Video".
4. Tap "Choose from device".
5. Thumbnails of images should not be shown

Screenshots

Before

Before	After
RPReplay_Final1639256947.MP4	RPReplay_Final1639257162.MP4

Regression Notes

1. Potential unintended areas of impact
   Any blocks that allow uploading media from the device such as the Image, Gallery, Video, and Media & Text blocks.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   I manually tested this on a device.

3. What automated tests I added (or what prevented me from doing so)
   None.

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.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[ttahmouch]

I feel weird approving the changes because I'm not super familiar with the code, but if you'd like to also seek a second opinion I totally understand.

[twstokes]

I feel weird approving the changes because I'm not super familiar with the code, but if you'd like to also seek a second opinion I totally understand.

No worries! Thanks for taking the time and providing your feedback. I can also get a glance from an iOS dev.

[frosty]

Looks good to me, and fixes the issue!